Cxcr4 binding molecules

ABSTRACT

The present disclosure relates to polypeptides (also referred to herein as CXCR4 binding molecules or polypeptides) that are directed against the G-coupled protein receptor CXCR4, also known as Fusin or CD184. The invention also relates to nucleic acids encoding such polypeptides; to methods for preparing such polypeptide; to compositions, and in particular to pharmaceutical compositions that comprise such polypeptides and to uses of such polypeptides for therapeutic or diagnostic purposes.

RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

All documents cited or referenced herein, and all documents cited orreferenced in herein cited documents, together with any manufacturer'sinstructions, descriptions, product specifications, and product sheetsfor any products mentioned herein or in any document incorporated byreference herein, are hereby incorporated herein by reference in theirentirety.

This document claims priority from AU 2015900054 the entire contents ofwhich are incorporated by reference.

The entire content of the electronic submission of the sequence listingis incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present disclosure relates to polypeptides (also referred to hereinas CXCR4 binding molecules or polypeptides) that are directed againstthe G-coupled protein receptor CXCR4, also known as Fusin or CD184. Theinvention also relates to nucleic acids encoding such polypeptides; tomethods for preparing such polypeptide; to compositions, and inparticular to pharmaceutical compositions that comprise suchpolypeptides and to uses of such polypeptides for therapeutic ordiagnostic purposes.

BACKGROUND OF THE INVENTION

Chemokines (chemoattractant cytokines) are a family of structurally andfunctionally related small proteins that direct migration of cells(e.g., leukocytes and/or lymphocytes and/or stem cells and/or neurons)in addition to controlling other biological processes, such asangiogenesis, morphogenesis, autoimmunity, tumor growth and metastasis.Chemokines are grouped into families based on the presence and relativeposition of amino terminal cysteine residues (e.g. CC, CXC, CX₃C and Cchemokines). Generally, the biological activity of a chemokine ismediated by a cell surface receptor, in particular a7-transmembrane-domain G protein-coupled receptor (GPCR). The chemokinereceptors are grouped and named according to the family of chemokine(s)to which they bind.

One member of the CXCR family is CXCR4 that is predominantly expressedon lymphocytes and that activates chemotaxis. CXCR4, also called fusin,is an alpha-chemokine receptor specific for stromal-derived-factor-1(SDF-1, also called CXCL12), a molecule endowed with potent chemotacticactivity for lymphocytes.

CXCR4 plays a role in embryogenesis, homeostasis, fibrosis andinflammation. The CXCR4/SDF-1 pathway has been implicated in organvascularisation, as well as in the immune and hematopoietic systems(Tachibana K et al. (1998) Nature 393:591-594). Drugs that block theCXCR4 receptor appear to be capable of “mobilising” hematopoietic stemcells into the blood stream as peripheral blood stem cells. CXCR4 hasalso been shown to function as a co-receptor for T lymphorophic HIV-1isolates (Geng Y et al. (1996) Science 272:872-877). CXCR4 has also beenshown to be expressed on a wide variety of cancer cell types and to beinvolved in stimulating the metastatic process in many differentneoplasms (Murphy P M (20001) N. Eng. J. Med. 345:833-835).

G-protein coupled receptors are currently the most important class oftherapeutic targets, and antibodies directed against them are highlysought for therapeutic, diagnostic and research purposes. Despitesubstantial interest in these targets, high-quality antibodies orbinding agents against membrane proteins have been challenging togenerate using conventional means.

Binding agents to CXCR4 have previously been described, including wholeantibodies (e.g. Medarex), antibody fragments and single-domainantibodies (Ablynx), however the present binding agents provide analternative construct which alleviates some of the drawbacks ofantibodies, for example, Fc-mediated effects as well as high productioncosts, low stability and their large size, which reduce their utilityfor tumor penetration. The binding agents of the present inventionprovide an alternative to small molecule agents such as Plerixafor(Mozobil or AMD3100) which is currently indicated for peripheral bloodstem cell mobilisation in combination with granulocyte colonystimulating factor (G-CSF) in patients with non-Hodgkins' lymphoma (NHL)and multiple myeloma (MM).

SUMMARY OF THE INVENTION

The present disclosure relates to CXCR4 binding molecules orpolypeptides, referred to as “i-bodies” in the examples describedherein. These i-bodies bind to native human CXCR4 expressed on a cellsurface. The i-bodies of the present disclosure can be used to modulate,and in particular inhibit or prevent CXCR4 mediated signalling and/or tomodulate the biological pathways in which CXCR4 is involved and/or tomodulate the biological mechanisms, responses and effects associatedwith such signalling. As such, the i-bodies of the present disclosurecan be used for the prevention and treatment of CXCR4-related diseasesand disorders.

It will be appreciated that CXCR4 binding molecules or i-bodies of thepresent disclosure provide advantages over other binding agents such astraditional antibodies. Like traditional antibodies, the i-bodies of thepresent disclosure are able to bind to their target with high affinityand high specificity but their smaller size and stability areadvantageous when compared to traditional therapeutic antibodies,polypeptides or peptides. I-bodies are also more stable molecules thanconventional antibodies which leads to alternative routes ofadministration and to lower dose form, less frequent dosage, and lessside effects. I-bodies are also smaller in size and therefore canpenetrate tissues, organs and areas such as the bone matrix andmicro-tumor environment that other large proteins may not be able topenetrate. I-bodies also have a long CDR3 binding loop that is able topenetrate grooves and clefts unlike traditional monoclonal antibodies.The i-bodies of the present disclosure are able to bind deep into thepocket of the CXCR4 G-protein coupled receptor (GPCR).

Due to their relatively small size, the i-body is ideally suited fortailoring half life which will have advantages when used as an imagingagent or in the delivery of a required dose for a set period of time. Asa small polypeptide, the i-body also provides the delivery of a pay-loadto the target through conjugation to the identified polypeptide.

Additionally, the inventors have found that the CXCR4 bindingpolypeptides/i-bodies of the present disclosure have features thatdistinguish them over other inhibitor/antagonist CXCR4 binding moleculesknown in the art. In particular, the CXCR4 binding polypeptides/i-bodiesof the present disclosure do not cause stem cell mobilisation.Additionally, the CXCR4 binding polypeptides/i-bodies of the presentdisclosure do not inhibit calcium flux.

The present disclosure provides a polypeptide which comprises a scaffoldregion and complementarity determining regions (CDR1 and CDR3) containedtherein, wherein the scaffold region comprises a sequence which has atleast 75% identity to the scaffold region defined by amino acids 1 to26, 33 to 79 and 88 to 97 of SEQ ID NO:1 and wherein the CDR1 and CDR3region defined by amino acids 27 to 32 and 80-87 respectively of SEQ IDNO:1 are modified by amino acid addition or substitution therein andwherein the polypeptide binds to human CXCR4.

In one example, the polypeptide comprises the sequence set forth in SEQID NO:2 (FIG. 1B) or the sequence set forth in SEQ ID NO:2 or thesequence set forth in SEQ ID NO:2 comprising between 1 and 5 amino acidadditions or substitution therein.

In one example, the CDR1 region consists of a random sequence of sixconsecutive amino acid residues (designed XXXXXX in FIG. 1B) and theCDR3 region is represented by Y′n (in FIG. 1B), wherein Y is any aminoacid residue and n is any number between 10 and 20 amino acidsinclusive. The CDR1 and/or CDR3 regions of SEQ ID NO:2 are modified byamino acid addition and/or substitution relative to the correspondingCDR1 and/or CDR3 regions in SEQ ID NO:1.

In one example, the amino acid A′ at position 23 of SEQ ID NO:2 is theamino acid glutamine (Q) or lysine (K).

In one example, the amino acid B′ at position 24 of SEQ ID NO:2 is theamino acid valine (V) or alanine (A).

In one example, A′ is Q and B′ is V in SEQ ID NO:2.

The polypeptide may further comprise between 1 and 4 consecutiveN-terminal amino acids selected from the group consisting of M, EAEA, MAor MP.

In one example, the polypeptide binds to human CXCR4. In a furtherexample, the polypeptide is an antagonist of human CXCR4.

In one example, the polypeptide binds to human CXCR4 with an affinity ofless than 50 uM, less than 20 uM, less than 10 uM, less than 1 μM, lessthan 850 nM, less than 700 nM, less than 600 nM, less than 500 nM, lessthan 300 nM, less than 100 nM, less than 50 nM, less than 25 nM, lessthan 20 nM, less than 15 nM, less than 10 nM, or less than 5 nM. In aparticular example, the polypeptide binds to human CXCR4 with anaffinity of about 700 nM. In a particular example, the polypeptide bindsto human CXCR4 with an affinity of less than 700 nM.

In one example, the scaffold region comprises a sequence which has atleast 80%, or at least 85%, or at least 90%, or at least 95%, or atleast 97%, or at least 98%, at least 99% identity, or 100% identity toSEQ ID NO:1 at positions 1 to 26, 33-79 and 88-97.

In one example, the scaffold region comprises a sequence which has atleast 80%, or at least 85%, or at least 90%, or at least 95%, or atleast 97%, or at least 98%, at least 99% homology, or 100% homology toSEQ ID NO:1 at positions 1 to 26, 33-79 and 88-97.

In one example the polypeptide according to SEQ ID NO:1 or SEQ ID NO:2is modified by one or more amino acid substitutions.

In one example the CDR1 and CDR3 region is modified by one or more aminoacid substitutions. In another embodiment the CDR1 and/or CDR3 region ismodified by replacement with a random loop sequence.

In one example the CDR3 region comprises or consists of a sequencehaving at least 70% identity, or at least 80% identity, or at least 90%identity, or at least 95% identity, or at least 97% identity, or atleast 98% identity, or at least 99% identity, or 100% identity to SEQ IDNO: 13, SEQ ID NO: 16, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQID NO: 28, or SEQ ID NO: 31.

In one example the CDR3 region comprises or consists of a sequencehaving at least 70% homology, or at least 80% homology, or at least 90%homology, or at least 95% homology, or at least 97% homology, or atleast 98% homology, or at least 99% homology, or 100% homology to SEQ IDNO: 13, SEQ ID NO: 16, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQID NO: 28, or SEQ ID NO: 31.

In another example, CDR3 region comprises or consists of a sequencehaving at least one, two, three, four, five or six substitutions withina sequence selected from SEQ ID NO: 13, SEQ ID NO: 16, SEQ ID NO: 19,SEQ ID NO: 22, SEQ ID NO: 25, SEQ ID NO: 28, or SEQ ID NO: 31.

In another example, CDR3 region comprises or consists of SEQ ID NO: 13.

In one example the CDR1 region comprises or consists of a sequencehaving at least 50% identity, or at least 65% identity, or at least 80%identity, or 100% identity to SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO:18, SEQ ID NO: 21, SEQ ID NO: 24, SEQ ID NO: 27, or SEQ ID NO: 30.

In one example the CDR1 region comprises or consists of a sequencehaving at least 50% homology, or at least 65% homology, or at least 80%homology, or 100% homology to SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO:18, SEQ ID NO: 21, SEQ ID NO: 24, SEQ ID NO: 27, or SEQ ID NO: 30.

In another example, CDR1 region comprises or consists of a sequencehaving at least one, two or three substitutions within SEQ ID NO: 12,SEQ ID NO: 15, SEQ ID NO: 18, SEQ ID NO: 21, SEQ ID NO: 24, SEQ ID NO:27, or SEQ ID NO: 30.

In another example, the CDR1 region comprises or consists of SEQ ID NO:12.

In another example, the polypeptide comprises:

-   -   (i) a CDR1 region sequence having at least 50% identity to SEQ        ID NO: 12 and a CDR3 region sequence having at least 70%        identity to SEQ ID NO: 13;    -   (ii) a CDR1 region sequence having at least 50% homology to SEQ        ID NO: 12 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 13;    -   (iii) a CDR1 region sequence having at least 50% identity to SEQ        ID NO: 15 and a CDR3 region sequence having at least 70%        identity to SEQ ID NO: 16;    -   (iv) a CDR1 region sequence having at least 50% homology to SEQ        ID NO: 15 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 16;    -   (v) a CDR1 region sequence having at least 50% identity to SEQ        ID NO: 18 and a CDR3 region sequence having at least 70%        identity to SEQ ID NO: 19;    -   (vi) a CDR1 region sequence having at least 50% homology to SEQ        ID NO: 18 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 19;    -   (vii) a CDR1 region sequence having at least 50% identity to SEQ        ID NO: 21 a the CDR3 region sequence having at least 70%        identity to SEQ ID NO: 22;    -   (viii) a CDR1 region sequence having at least 50% homology to        SEQ ID NO: 21 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 22;    -   (ix) a CDR1 region sequence having at least 50% identity to SEQ        ID NO: 24 and a CDR3 region sequence having at least 70%        identity to SEQ ID NO: 25;    -   (x) a CDR1 region sequence having at least 50% homology to SEQ        ID NO: 24 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 25;    -   (xi) a CDR1 region having at least 50% identity to SEQ ID NO: 27        and a CDR3 region sequence having at least 70% identity to SEQ        ID NO: 28;    -   (xii) a CDR1 region sequence having at least 50% homology to SEQ        ID NO: 27 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 28;    -   (xiii) a CDR1 region sequence having at least 50% identity to        SEQ ID NO: 30 and a CDR3 region sequence having at least 70%        identity to SEQ ID NO: 31; or    -   (xiv) a CDR1 region sequence having at least 50% homology to SEQ        ID NO: 30 and a CDR3 region sequence having at least 70%        homology to SEQ ID NO: 31.

In one example, the polypeptide comprises a sequence that has at least80% identity, at least 90% identity, or at least 95% identity, or atleast 97% identity, or at least 98% identity, or at least 99% identityto SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ IDNO: 23, SEQ ID NO: 26, or SEQ ID NO: 29.

In one example, the polypeptide comprises a sequence that has at least70% homology, or at least 80% homology, or at least 90% homology, or atleast 95% homology, or at least 98% homology, or at least 99% homologyto SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ IDNO: 23, SEQ ID NO: 26, or SEQ ID NO: 29.

In one example, the polypeptide comprises a sequence set forth in anyone of SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQID NO: 23, SEQ ID NO: 26, or SEQ ID NO: 29.

In one example the polypeptide comprises one, two, three, four, five,six, seven, eight, nine or ten substitutions within the sequenceselected from the group consisting of SEQ ID NO: 11, SEQ ID NO: 14, SEQID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29,SEQ ID NO:40, SEQ ID NO:44, SEQ ID NO:48, SEQ ID NO:52, SEQ ID NO:56,SEQ ID NO:60, SEQ ID NO:64, SEQ ID NO:68, SEQ ID NO:72, or SEQ ID NO:76.

In one example the polypeptide comprises or consists of SEQ ID NO: 11.

In a further example, polypeptide comprises a CDR1 region comprising asequence represented by the formula SX₁SX₂X₃R wherein

X₁ is G, K, L or Y; X₂ is D, H, G or N; and X₃ is is I, V, M, F, Q or Y;

or a conservative amino acid substitution thereof.

In one example, the CDR1 region comprises or consists of the sequenceset forth in any one of SEQ ID NO: 41, SEQ ID NO: 45, SEQ ID NO: 49, SEQID NO: 53, SEQ ID NO:57, SEQ ID NO:61, SEQ ID NO:65, SEQ ID NO:69, SEQID NO: 73, or SEQ ID NO:77.

In one example, the polypeptide comprises a CDR3 region comprises asequence represented by the formula Y′₁RY′₂GY′₃YRHRY′₄LY′₅LG wherein.

Y′₁ is Y or W;

Y′₂ is T, V or I;

Y′₃ is G or A;

Y′₄ is A or Y; and

Y′₅ is V, R or K;

or a conservative amino acid substitution thereof.

In one example, the CDR3 region comprises or consists of the sequenceset forth in any one of SEQ ID NO: 42, SEQ ID NO: 46, SEQ ID NO: 50, SEQID NO: 54, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 66, SEQ ID NO: 70,SEQ ID NO: 74, or SEQ ID NO: 78.

In another example, the polypeptide comprises a sequence at least 70%identical to a sequence selected from the group consisting of SEQ ID NO:40, SEQ ID NO: 44, SEQ ID NO: 48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ IDNO: 60, SEQ ID NO: 64, SEQ ID NO: 68, SEQ ID NO: 72 or SEQ ID NO: 76.

In another example, the polypeptide comprises a sequence at least 75%,80%, 85%, 87%, 90%, 93%, 95%, 98%, or 99% identical to a sequenceselected from the group consisting of SEQ ID NO: 40, SEQ ID NO: 44, SEQID NO: 48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQ ID NO: 64,SEQ ID NO: 68, SEQ ID NO: 72 or SEQ ID NO: 76.

In another example, the polypeptide comprises a sequence represented bythe sequence

(SEQ ID NO: 39) ZLQVDIVPSQGEISVGESKFFLCA′B′AGSX ₁SX ₂ X ₃RISWFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVY′₁RY′₂GY′₃ YRHRY′₄LY′₅LGEATVNVKIFQwherein

A′ is Q or K;

B′ is V or A;

X₁ is G, K, L or Y;

X₂ is D, H, G or N;

X₃ is I, V, M, F, Q or Y;

Y′₁ is Y or W;

Y′₂ is T, V or I;

Y′₃ is G or A;

Y′₄ is A or Y; and

Y′₅ is V, R or K;

or a conservative amino acid substitution thereof; andZ is an amino acid(s) selected from M, EAEA, MA or MP or is absent.

In another example, the polypeptide comprises or consists of thesequence set forth in any one of SEQ ID NO: 40, SEQ ID NO: 44, SEQ IDNO: 48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQ ID NO: 64, SEQID NO: 68, SEQ ID NO: 72 or SEQ ID NO: 76.

In another example, the polypeptide comprises or consists of thesequence set forth in SEQ ID NO: 40.

In one example, the K_(D) of the polypeptide for human CXCR4 is betweenabout 0.01 nM to about 700 nM, such as between about 0.05 nM to about500 nM, for example between about 0.1 nM to about 100 nM, for examplebetween about 1 nM to about 50 nM, between about 5 nM to about 30 nM,between about 10 nM to about 20 nM or between about 3 nM to about 16 nM,

In another example, the polypeptide binds to human CXCR4 with anaffinity between 3 nM and 10 nM. In another example, the polypeptidebinds to human CXCR4 with an affinity between 3 nM and 5 nM.

In one example, the K_(D) is assessed by immobilizing the human CXCR4and assessing binding of the polypeptide to the immobilized human CXCR4using surface plasmon resonance. In one example, the assessment ofbinding of the polypeptide is to immobilised CXCR4 lipoparticles.

An exemplary polypeptide of the disclosure has a K_(D) of about 5 nM(e.g., +/−1 nM) for human CXCR4.

In another example, the association rate (Ka) is between about 1×10⁴M⁻1s⁻1 to about 10×10⁵ M⁻1s⁻¹, for example between about 5×10⁴ M⁻¹s⁻¹,to about 8.5×10⁵ M⁻¹s⁻¹, for example, between about 1×10⁵ M⁻¹s⁻¹ toabout 6×10⁵ M⁻¹s⁻¹, for example between 6×10⁵ M⁻¹s⁻¹ to 1×10⁶ M⁻¹s⁻¹. Inone example, the Ka is assessed by immobilizing the human CXCR4 andassessing binding of the molecule to the immobilized human CXCR4 usingsurface plasmon resonance.

In another example, the dissociation rate (Kd) is between about 0.005M⁻¹s⁻¹ to about 0.9 M⁻¹s⁻¹, for example between about 0.02 M⁻¹s⁻¹ toabout 0.7 M⁻¹s⁻¹, for example between about 0.2 M⁻¹s⁻¹ and 0.55 M⁻¹s⁻¹.

An exemplary polypeptide of the disclosure has a K_(a) of about1.297×10⁶M⁻¹s⁻¹. A further exemplary binding polypeptide of thedisclosure has a K_(d) of about 0.00629 M⁻¹s⁻¹. In one example, the Kaand Kd are assessed by immobilizing a lipoparticle expressing humanCXCR4 and assessing binding of the polypeptide to the immobilizedlipoparticle expressing human CXCR4 using surface plasmon resonance.

Residues involved in the binding of the polypeptides of the presentdisclosure to CXCR4 have been determined and are disclosed herein. Inone example, the disclosure provides a CXCR4 binding polypeptide asdescribed herein, that binds to one or more core residues of human CXCR4selected from the group consisting of E32, Y184, F189, W195, D262 andL266 or combinations of any of these. In another example, the residue isselected from the group consisting of E32K, Y184S, F189L, W195R, D262Gand L266H or a combination of any of these. In another example, thedisclosure provide a CXCR4 binding polypeptide as described herein thatbinds to one or more residues of CXCR4 selected from the groupconsisting of C28, V112, D193, P191, E268 and E288 or combinations ofany of these. In another example, the residue is selected from the groupconsisting of C28W, V112A, D193G, P191T, E268K and E288G or acombination of any of these. The amino acid residues being substitutedare numbered according to the canonical sequence of human CXCR4 havingUniprot sequence identifier number P61073-1 (SEQ ID NO: 105).

The CXCR4 binding polypeptides contact the same residues that have beenshown to be responsible for the binding of small molecules such asAMD3100 indicating that the CXCR4 binding polypeptides can penetratedeep into the CXCR4 binding pocket. In a particular example, thepolypeptide binds to the D262 position of CXCR4.

The polypeptide of the present disclosure can generally be used tomodulate CXCR4 mediated signalling, and/or to modulate the biologicalpathways in which CXCR4 is involved, and/or to modulate the biologicalmechanisms, responses and effects associated with such signalling orthese pathways.

In one example, the polypeptide can be used to modulate (i.e. inhibit,prevent, stimulate or boost) one or more of the following activities:

(i) calcium flux in cells expressing CXCR4;

(ii) cAMP in cells expressing CXCR4;

(iii) β-arrestin signalling in cells expressing CXCR4;

(iv) apoptosis in cells expressing CXCR4;

(v) cell proliferation of cells expressing CXCR4;

(vi) metastasis of cells expressing CXCR4;

(vii) CXCR4 induced angiogenesis; and

(viii) migration of cells expressing CXCR4.

In one example, tumor cell proliferation may be increased or decreasedby at least 30% preferably at least 50% or at least 60%, or 70% or 75%,or 80% or 90% or more, compared to the differentiation and orproliferation of tumor cells under the same condition without thepresence of the polypeptide.

In one example, the polypeptide can be used to inhibit tumor cellproliferation in a tumor cell proliferation assay with an IC₅₀ of lessthan 600 nM, less than 500 nM, less than 200 nM, less than 100 nM, lessthan 50 nM, less than 25 nM, less that 10 nM or less than 5 nM. In oneexample, the tumor cell proliferation assay is a 5-bromo-2′-deoxyuridinecell proliferation or CTG (CellTiter-Glo®) assay. In another example,the inhibition of tumor cell proliferation is determined by way of MTTassay.

In one example, induction of apoptosis in cells expressing CXCR4 by thepolypeptide of the present disclosure can be measured by caspase assay,tunnel and DNA fragmentation assay, cell permeability assay, annexin Vassay, protein cleavage assay and mitochondrial and ATP/ADP assay. Suchassays will be familiar to persons skilled in the art.

In one example, the polypeptide of the present disclosure can be usedinhibit metastases of CXCR4⁺ tumor cells, for example in a metastaticbreast cancer model with cells expressing CXCR4, for example MDA-MB-231or MDA-MB-468 cells.

Accordingly, the present disclosure also provides a method of inhibitingmetastasis of a cancer cell expressing CXCR4.

In one example, the polypeptide of present disclosure can be used toinhibit SDF-1 induced migration of cells expressing CXCR4, for examplein CEM, MDA-MB-231, MDA-MB-468, PC3 and Ramos cells.

In one example, the polypeptide of the present disclosure can be used toinhibit angiogenesis, which can be measured in a capillary tubeformation assay, for example with HUVEC cells or MDA-MB-231 cells.

In one example, the polypeptide of the present disclosure is used in thetreatment or prevention of a CXCR4-related disease or disorder in asubject.

The human CXCR4 to which the polypeptide binds may be in monomeric,dimeric or multimeric form. For example, the human CXCR4 may be in theform of a heterodimer. Examples of CXCR heterodimers that have beendescribed include CXCR4/CXCR7 (Levoye et al Blood 2009 113; 6085-6093),CXCR4/CCR2 (Sohy et al J Biol Chem. 2007 282; 30062-30069), CXCR4/β2AR(β2 adrenergic receptor) (La Rocca et al J Cardiovasc Pharmacol. 201056; 548-559), CXCR4/CCR5 (Sohy et al J Biol Chem. 2009 284;31270-31279), CXCR4/DOR (Delta opiod receptor) (Pello et al Eur. J.Immunol. 2008 38; 537-549). CXCR4 has also been shown to interact withthe T cell receptor (Kremer et al J. Immunol. 2011 187; 1440-1447).These dimers can modulate the SDF-1 induced signaling outcomes and thei-body antagonists described may also alter the signaling consequencesas compared to the CXCR4 as a monomer.

In one example, the polypeptide of the present disclosure binds to atransmembrane or other domain which influences the structure of CXCR4.

In another example, the polypeptide of the present disclosurespecifically binds to any suitable extracellular part, region, domain,loop or extracellular epitope of CXCR4. In one example, the polypeptidespecifically binds to one of the extracellular parts of thetransmembrane domains or to one of the extracellular loops that linksthe transmembrane domains.

In another example the polypeptide of the disclosure is PEGylated.

The present disclosure also provides a nucleic acid molecule encoding apolypeptide described herein.

In one example the nucleic acid molecule comprises a sequence that hasat least 80% identity, at least 90% identity, or at least 95% identity,or at least 97% identity, or at least 98% identity, or at least 99%identity, or 100% identity to any one of SEQ ID NO: 32, SEQ ID NO: 33,SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO:38, SEQ ID NO: 43, SEQ ID NO: 47, SEQ ID NO: 51, SEQ ID NO: 55, SEQ IDNO: 59, SEQ ID NO: 63, SEQ ID NO: 67, SEQ ID NO: 71, SEQ ID NO: 75, orSEQ ID NO: 79.

In one example the nucleic acid molecule comprises a sequence that hasat least 80% homology, at least 90% homology, or at least 95% homology,or at least 97% homology, or at least 98% homology, or at least 99%homology, or 100% homology to any one of SEQ ID NO: 32, SEQ ID NO: 33,SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO:38, SEQ ID NO: 43, SEQ ID NO: 47, SEQ ID NO: 51, SEQ ID NO: 55, SEQ IDNO: 59, SEQ ID NO: 63, SEQ ID NO: 67, SEQ ID NO: 71, SEQ ID NO: 75, orSEQ ID NO: 79.

In one example, the nucleic acid molecule encodes a poypeptide selectedfrom the group consisting of SEQ ID NO: 40, SEQ ID NO: 44, SEQ ID NO:48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQ ID NO: 64, SEQ IDNO: 68, SEQ ID NO: 72, or SEQ ID NO: 76.

The present disclosure also provides an expression construct comprisinga nucleic acid molecule described herein.

The present disclosure also provides a host cell comprising the nucleicacid molecule or expression construct described herein.

The present disclosure also provides a method of producing a polypeptideof the present disclosure which comprises culturing a host cell underconditions enabling expression of the polypeptide and recovering thepolypeptide.

The present disclosure also provides a conjugate (e.g. immunoconjugate)comprising a polypeptide described herein and an agent.

The agent may be, for example, a therapeutic agent, a toxin, adetectable label or an agent which extends the half life of thepolypeptide. In one example, the agent is polyethylene glycol (PEG). Inanother example, the agent is a consecutive sequence of Pro-Ala-Ser(PAS).

In one example the agent which extends the half life of the polypeptidebinds to a serum protein (e.g. albumin) or an Fc portion of animmunoglobulin.

In another example the polypeptide of the invention may be linked to atoxin or cytotoxic drug for delivery to cells such as tumour cells.

In another example the polypeptide of the invention may be linked to alabel such as a radioisotope.

The present disclosure also provides a multimer comprising two or morepolypeptides described herein. The polypeptides may comprise the same ordifferent amino acid sequences. For example, in its simplest form, atleast two polypeptides are directly linked via a suitable linker orsequence or spacer. For example, the linker or spacer can be between 1and 50 amino acids. For example, a suitable linker is a GS9 linker orGS15 linker or a GS20 linker.

The present disclosure also provides for multivalent or multispecificpolypeptides (including bi-specific polypeptides). In one example thedisclosure provides a polypeptide of the present disclosure linked to apolypeptide directed to a target other than CXCR4, including by notlimited to, human serum albumin to increase half-life, CD3, CD64, CD16or CD89 to redirect and activate any circulating T cells against tumors.In a particular example, the multispecific polypeptide is a bi-specificpolypeptide which binds to CXCR4 and human serum albumin (HSA), thepolypeptide comprising the sequence of SEQ ID NO:80.

The present disclosure also provides a pharmaceutical compositioncomprising a polypeptide or a conjugate or a multimer as describedherein and an acceptable carrier.

The present disclosure also provides a polypeptide, a conjugate or amultimer according to the present disclosure for use in the treatment orprevention of a CXCR4-related disease or disorder, the polypeptidecomprising a sequence selected from the group consisting of SEQ ID NO:11, SEQ ID NO:14, SEQ ID NO:17, SEQ ID NO:20, SEQ ID NO:23, SEQ IDNO:26, SEQ ID NO:29, SEQ ID NO: 40, SEQ ID NO: 44, SEQ ID NO: 48, SEQ IDNO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQ ID NO: 64, SEQ ID NO: 68, SEQID NO: 72, or SEQ ID NO: 76.

In one example the polypeptide of the present disclosure bindsspecifically to human CXCR4.

The present disclosure also provides a method of preventing or treatinga CXCR4-related disease or disorder or a disease or disorder associatedwith CXCR4 signalling or a pathway or mechanism in which CXCR4 isinvolved, comprising administering to a subject in need thereof apolypeptide or a conjugate or a multimer of the present disclosure.

In one example, the polypeptide comprises a sequence selected from thegroup consisting of SEQ ID NO: 11, SEQ ID NO:14, SEQ ID NO:17, SEQ IDNO:20, SEQ ID NO:23, SEQ ID NO:26, SEQ ID NO:29, SEQ ID NO: 40, SEQ IDNO: 44, SEQ ID NO: 48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQID NO: 64, SEQ ID NO: 68, SEQ ID NO: 72, or SEQ ID NO: 76.

Diseases or disorders amenable to treatment with the polypeptide,nucleic acid molecule, conjugate or multimer of the present disclosureinclude cancers (for example, hematopoietic cancers: CLL, AML, ALL, MM,NHL; solid tumors: breast cancer, lung cancer, brain tumors; stromalchemoresistance of tumors; leukemia and other cancers), viral infections(e.g. HIV/AIDS, West Nile Virus encephalitis), inflammatory disease(e.g. rheumatoid arthritis, asthma, systemic lupus erythematosus;neuro-inflammatory diseases), fibrosis, for example, lung (pulmonaryfibrosis), systemic sclerosis, kidney disease (diabetic nephropathy,FSGS as examples), liver, eye (uveitis, AMD, diabetic retinopathy);immune deficiency disorders; multiple sclerosis, and stroke. Tissue andwound healing including scarring, burns, or radiation induced burns.

In one particular example, the CXCR4-related disease or disorder isfibrosis. In a further example, the disorder is idiopathic pulmonaryfibrosis (IPF). In another particular example, the CXCR4-related diseaseor disorder is kidney disease.

In another example, the CXCR4-related disease or disorder is multiplesclerosis.

In another example, the CXCR4-related disease or disorder isatherosclerosis.

In another example, the CXCR4-related disease or disorder is HIV.

The polypeptide of the present disclosure may or may not cause stem cellmobilisation. In one example, the present disclosure also provides amethod for peripheral blood stem cell mobilisation, comprisingadministering to a subject in need thereof a polypeptide, nucleic acidmolecule, conjugate or multimer of the present disclosure. In oneexample, the peripheral blood stem cells are used for autologous stemcell transplantation. In one example, the subject in need thereof hasmultiple myeloma, acute myeloid leukemia or non-Hodgkin's lymphoma. In afurther example, the stem cells are CD34+ cells.

In general, antibodies directed to CXCR4 have been shown to mobilisestem cells which is not desirable for a therapeutic approach in someindications. The polypeptides of the present disclosure do notsubstantially cause stem cell mobilisation. In one example, mobilisationof stem cells is reduced by a polypeptide of the present disclosure byat least 50%, at least 60%, at least 70%, at least 80% or at least 90%compared to the control AMD3100.

In another example, the polypeptide does not substantially inhibitcalcium flux.

The present disclosure also provides a functional fragment of a CXCR4binding polypeptide described herein. In one example, the functionalfragment comprises the CDR3 sequence of a CXCR4 binding moleculedescribed herein. By “functional fragment” we mean a fragment whichbinds to human CXCR4 with an affinity which is substantially similar orimproved when compared to the full length polypeptide from which it isderived, and which inhibits or prevents CXCR4 mediated signalling.Preferably, the fragment binds to one or more core residues of humanCXCR4 selected from the group consisting of E32, Y184, F189, W195, D262and L266 or combinations of any of these.

In a further example, the functional fragment comprises a sequenceselected from the group consisting of SEQ ID NO: 13, SEQ ID NO: 16, SEQID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQ ID NO: 28, SEQ ID NO: 31,SEQ ID NO: 42, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 54, SEQ ID NO:58, SEQ ID NO: 62, SEQ ID NO: 66, SEQ ID NO: 70, SEQ ID NO: 74, or SEQID NO: 78.

The present disclosure further provides a peptide mimetic based on aCXCR4 binding polypeptide described herein or a portion thereof, such asa CDR3 sequence of a CXCR4 binding polypeptide described herein. Thepeptide mimetic may be based on, or derived from a sequence selectedfrom the group consisting of SEQ ID NO: 13, SEQ ID NO: 16, SEQ ID NO:19, SEQ ID NO: 22, SEQ ID NO: 25, SEQ ID NO: 28, SEQ ID NO: 31, SEQ IDNO: 42, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 54, SEQ ID NO: 58, SEQID NO: 62, SEQ ID NO: 66, SEQ ID NO: 70, SEQ ID NO: 74, or SEQ ID NO:78. The present disclosure also contemplates compositions comprising oneor more mimetic peptides for use in treating a CXCR4 related disease ordisorder, in particular a CXCR4 related disease or disorder describedherein.

The present disclosure additionally provides the polypeptide or thenucleic acid or the expression construct, or the cell or the compositionof the present disclosure for use in the treatment or prophylaxis of aCXCR4-related disease or disorder.

The present disclosure additionally provides for use of the polypeptideor the nucleic acid or the expression construct or the cell or thecomposition of the present disclosure in medicine.

The present disclosure also provides use of a polypeptide or the nucleicacid or the expression construct or the cell or the composition of thepresent disclosure for the treatment or prophylaxis of a CXCR4-relateddisease or disorder.

In one particular example, the CXCR4-related disease or disorder isfibrosis. In another particular example, the CXCR4-related disease ordisorder is lung fibrosis. In another example it is liver fibrosis. Inanother example it is a fibrosis related condition of the eye. Inanother example it is skin fibrosis. In yet another example it is kidneyfibrosis.

The present disclosure additionally provides for use of the polypeptideor the nucleic acid or the expression construct or the cell of thepresent disclosure in the manufacture of a medicament for the treatmentor prophylaxis of a CXCR4-related disease or condition.

The polypeptide of the present disclosure can also be used in adiagnostic format.

The present disclosure therefore additionally provides a method fordetecting CXCR4 in a sample obtained from a subject, the methodcomprising contacting a sample with the polypeptide of the disclosuresuch that a CXCR4-polypeptide complex forms and detecting the complex,wherein detecting the complex is indicative of CXCR4 in the sample. Inone example, the sample is from a subject suffering from CXCR4-relateddisease or condition. In a further example, the sample is a biologicalsample.

The present disclosure also provides a method for detecting a complex ofCXCR4 binding polypeptide bound to human CXCR4 in a subject or in asample obtained from a subject, the method comprising allowing saidcomplex to form and detecting the formed complex. In one example, thehuman CXCR4 may be a dimer, trimer or multimer. Methods of detectingforming complexes will be familiar to persons skilled in the art.Examples include western blot analysis or surface plasmon resonance(biacore). Alternatively, fluorescent based methods may be used wherethe formation of the complex results in a fluorescently detectablesignal being produced which may or may not be quantified.

The present disclosure also provides a complex of a CXCR4 bindingpolypeptide of the disclosure bound to human CXCR4. The human CXCR4portion of the complex may be in the form of a dimer, trimer ormultimer.

The present disclosure additionally provides a method for diagnosing aCXCR4-related disease or disorder in a subject, the method comprisingperforming the method described herein for detecting CXCR4 in a samplefrom the subject, wherein detection of CXCR4 in the sample is indicativeof the disease or disorder.

In one example, the method comprises determining the level of CXCR4 inthe sample, wherein an increased or decreased level of CXCR4 in thesample compared to a control sample is indicative of the disease ordisorder.

The present disclosure additionally provides a method for localizingand/or detecting and/or diagnosing and/or prognosing a CXCR4-relateddisease or disorder, the method comprising detecting in vivo thepolypeptide of the present disclosure bound to CXCR4, if present,wherein the polypeptide is conjugated to a detectable tag.

In one example, the method additionally comprises administering thepolypeptide to the subject.

In one example of any method oftreatment/prophylaxis/diagnosis/prognosis described herein the CXCR4related disease or disorder is a cancer, viral infection (e.g. HIV),inflammatory disease, neuro-inflammatory diseases; fibrosis, immunedeficiency disorder; multiple sclerosis, hot flash or stroke. In afurther example, the CXCR4 related disease or disorder is fibrosis,cancer or inflammation.

The term “subject” according to the present disclosure is intended toinclude human and non-human animals. Non-human animals include allvertebrates, e.g., mammals and non-mammals, such as non-human primates,sheep, dogs, cats, cows, horses, chickens, amphibians, and reptiles.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagrammatic representation showing the sequence of thehuman NCAM domain 1 (A); the i-body scaffold and CDR1 (represented byXXXXXX) and CDR3 (represented by Yn) (B); sequence of a specific CXCR4binder, ADCX-99 (C) and consensus sequence for affinity matured bindersof ACDX-99 (D). X and Y are any amino acid, n is a number between 10 and20 inclusive. A′, B′ is any amino acid. Z is absent or amino acids M,EAEA, MA or MP.

FIGS. 2-1 and 2-2 show surface plasmon resonance (SPR; Biacore)affinities for (A) ADCX-306 (22.5 uM), (B) ADCX-272 (1.6 uM), and (C)ADCX-668 (42 uM).

FIGS. 3-1 to 3-3 shows β-arrestin activity for ADCX-99 (with Flag,Histidine (FH) and with IM7-FH protein tag), ADCX-6, ADCX-306, ADCX-668and ADCX-272 at various concentrations as indicated. All i-bodiesdemonstrated some degree of inhibition of β-arrestin.

FIG. 4 shows size exclusion chromatography (SEC) results for i-bodyADCX-99 protein (conjugated to IM7-FH (IM7 flag histidine taggedimmunity protein) purified from the periplasmic fraction. SEC wasconducted using a Superdex 75 column.

FIG. 5 shows surface plasmon resonance (SPR; BIAcore) of i-body ADCX-99for binding to immobilised CXCR4 positive lipoparticles (A). ADCX-99 didnot bind to null lipoparticles (B) or to CCR5 positive lipoparticles(C).

FIG. 6 shows 90 individual i-bodies from an affinity-matured mutantlibrary derived from i-body ADCX-99. The affinity-matured i-bodies weretested for expression by binding of anti-FLAG antibody compared tonegative controls ADCX-272 and ADR-3 and the wildtype i-body ADCX-99,which were grown under the same conditions and is provided in the lasttwo columns.

FIGS. 7-1 and 7-2 show 90 individual i-bodies from the affinity-maturedmutant library of i-body ADCX-99. The affinity matured i-bodies weretested for binding to CXCR4 positive lipoparticles (A) and to CCR5positive lipoparticles (B). Binding of the affinity matured i-bodies toCXCR4 and CCR5 positive lipoparticles is compared to binding of thewild-type i-body ADCX-99 (last two columns) and to the positive controli-body ADCX-272, and negative control i-body ADR-3.

FIG. 8 shows the sequence alignment of the affinity matured i-bodiesrelative to starting sequence ADCX-99.

FIG. 9 shows specificity of i-bodies (of Table 4) acting as antagonistsagainst a number of chemokine receptors expressed on cells and measuredby β-arrestin assay.

FIG. 10 shows individual sequence alignments for i-bodies AM4-661 (A),AM4-272 (B) and AM3-114, AM3-523 and AM5-245 relative to ADCX-99 (C).

FIG. 11 shows surface plasmon resonance (SPR; BIAcore) of bi-specificAM3-114-Im7-S21 binding to both CXCR4 and Human Serum Albumin (HSA). (A)binding of bi-specific i-body AM3-114-Im7-S21 to HSA by SA21 peptide(K_(D) 518 (+/−2) nM) at various concentrations 60 nM, 200 nM, 600 nMand 1.00 μM, (B) lack of binding by i-body AM3-114 to HSA at variousconcentrations 60 nM, 200 nM, 600 nM and 1.00 μM, (C) binding of i-bodyAM3-114 to CXCR4 (K_(D) 9 nM) and (D) binding of bi-specificAM3-114-Im7-S21 to CXCR4 (K_(D) 9 nM).

FIG. 12 shows the profile of i-body concentration following intravenousinjection of mice, as determined by quantitative mass-spectrometry.I-bodies (AM3-114, AM4-746) were conjugated to either IM7-FH,IM7-FH-SA21 or PEG (30K or 2×20K), and were compared to the unconjugatedcontrol, ADCX99-9×His.

FIG. 13 shows chemiluminescent signal detection of CXCR4 for i-bodiesAM3-114, AM4-272, AM3-523, AM4-746 and AM4-1121, positive controlAMD3100 and negative control i-body as measured by cAMP assay.

FIG. 14 shows the percent inhibition of Calcium flux measured by theQuest™ Fluo-8 kit for i-bodies AM3-114, AM4-272, AM3-523, AM4-746, andAM4-1121, control Ag (SDF-1), 21H5 negative control i-body and AMD3100positive control (effective concentration EC₈₀).

FIG. 15 shows the results of the BRET β-arrestin assay for (A)anti-CXCR4 i-body AM3-114 compared with two positive controls (smallmolecule AMD3100 and MAb12G5) and a negative control i-body; and (B)anti-CXCR4 i-bodies AM3-114, AM4-272, AM3-523, AM4-746, and AM4-1121,positive control (AMD3100) and ADCX-99.

FIGS. 16-1 to 16-3 show binding affinity as determined by flow cytometryof i-body AM3-114 to various cell lines that do not express CXCR4 T47D(A), and that express CXCR4 at various levels, including: Namalwa (B),MOLP8 (C), MOLT4 (D), Jurkat (E), CCRF-CEM (F), A498 (G), Ramos (H),NCI-H69 (I) and HL-60 (J). All cell lines were tested with i-bodyconcentrations of 10, 1 and 0.001 μM and in addition Namalwa cells (B)were tested with i-bodies at 4.7, 2.1, 0.47, 0.21, 0.1 and 0.01 μM.

FIG. 17 shows competition of CXCR4 i-bodies with SDF-1 for binding toCXCR4 positive lipoparticles measured by surface plamon resonance (SPR;BIAcore). Data shown for i-body AM3-114 (A) and AM4-272 (B).

FIG. 18 shows competition of CXCR4 i-body binding to Ramos cells withvarious molecules. AM3-114 (top panel), AM4-272 (middle panel), AM3-523(bottom panel) i-bodies bound to Ramos cells and this binding wasreduced to varying degrees upon the addition of AMD3100, MAb12G5 and thenatural ligand SDF-1.

FIGS. 19-1 and 19-2 show CXCR4 i-body induced apoptosis of Ramos cells.AM3-114 (AD-114), AM4-272 (AD-272), AM3-523 (AD-523) i-bodies bound toRamos cells and induced apoptosis as assessed by double staining ofannexin V and propidium iodide (top left quadrant in each of the flowcytometry traces). Untreated cells acted a negative control andthapsigargin is a well-described inducer of apoptosis (19-1).Quantitation of the flow cytometry traces is shown in the graphical form(19-2).

FIG. 20 shows the resuts of an HIV inhibition assay for i-bodiesAM3-272, AM3-114 and AM1-320 relative to a negative control i-body andthe positive control small molecule AMD3100.

FIG. 21 shows NP2-CD4/CXCR4 cell viability of i-bodies AM3-114, AM4-272,AM3-523, AM4-746 and AM4-1121 and control 21H5 measured using a FLUOStarmicroplate reader.

FIG. 22 shows inhibition of HIV strains (NL4.3 and 1109-F-30) withvarious i-bodies AM3-114, AM4-272, AM3-523, AM4-746 and AM4-1121relative to a negative control i-body 21H5. CXCR4 i-bodies blockinfection of of HIV in a dose dependent manner. VSVG is the Envelopefrom the Vesicular stomatitis virus that undergoes endocytosis afterbinding to an unrelated receptor.

FIGS. 23-1 and 23-2 show inhibition of HIV with PEGylated (30KDa and2×20KDa PEG) and non-PEGylated CXCR4 i-bodies AM3-114 and AM4-746. CXCR4i-bodies block infection of three strains of HIV in a dose-dependentmanner (A). The CXCR4 i-bodies are unable to block infection of a CCR5dependent strain of HIV (B).

FIG. 24 shows white blood cell count (A) of peripheral blood (PB) ofmice injected with i-bodies AM4-272, AM4-746, AM4-1121, AM3-114,AM3-523, or negative controls saline, isotype control i-body (21H5) orpositive control AMD3100; lack of mobilisation of LSK cells by thei-bodies is shown in (B) and lack of mobilisation of LSKSLAM cells bythe i-bodies is shown in (C).

FIG. 25 shows i-bodies AM3-114 and AM4-523 and negative control i-body21H5 do not mobilise stem cells compared to the positive control AMD3100in a humanised NODSIL2Rγ (NSG) mouse model. ns=not statiscallysignificant.

FIG. 26 shows CXCR4 i-bodies do not mobilize human stem and progenitors.In vitro binding experiments on sorted CD34⁺CD38⁻HSC (A) Representativedot plot of human CD34⁺CD38⁻ HSC. (B) Representative flow cytometrichistogram of i-body binding to human cord blood (CB) CD34⁺CD38⁻ HSC withAM3-114, AM4-272 and AM3-523 as indicated by arrows (C) Representativehistogram of AM3-114 binding to human BM CD34⁺CD38⁻ HSC andmuCD45⁻huCD45⁺CD34⁺CD38⁻ HSC from huNSG BM relative to control i-body(21H5).

FIG. 27 shows effect of i-bodies AM3-114 (A) and AM4-272 (B) onpro-fibrotic gene expression in laser treated mice. A panel of 85profibrotic genes were tested for mRNA levels in i-body treated mice.

FIG. 28 shows binding of AM3-114 i-body to human fibrocytes. Humanfibrocytes were identified by staining with an antibody to CD45. Bindingof i-body AM3-114 was identified by an anti-FLAG antibody to theC-terminal tag. DAPI was used to stain the nucleus of the cells. Thefinal panel is a merged image of all three stains.

FIG. 29 shows i-bodies AM3-114, AM4-272, AM3-523, AM4-746 and AM4-1121inhibiting leukocyte infiltration into a murine air pouch loaded withSDF-1 compared with a negative control i-body (which does not bind toCXCR4), positive controls AMD3100 and MSX-122 and a vehicle onlycontrol.

FIG. 30 shows the effect of i-bodies (AM3-114, AM4-272, AM3-523) atdifferent doses on intrapulmonary fibrocyte recruitment after bleomycininjury compared to positive controls AMD3100 and Pirfenidone andnegative control i-body (21H5). Fibrocytes were measured by staining thelung tissue from Bleomycin treated mice for CD45+CXCR4+Col 1+ cells.Percentage of cells that are fibrocytes is indicated on the Y axis.

FIGS. 31-1 to 31-3 show the effect of i-bodies (AM3-114, AM4-272,AM3-523), CXCR4 small molecule antagonist AMD3100 and negative controli-body 21H5 in inhibiting human IPF lung fibroblast invasion. Relativewound densities (%) of IPF lung fibroblast lines in the presence ofi-bodies. Fibroblasts from normal lung (A), from slow IPF progressor (B)and from a rapid IPF progressor (C). Arrows indicate i-body AM3-114which specifically inhibited migration of IPF lung fibroblasts (B andC), i-body AM4-272 inhibited fast progressor fibroblasts (C) but neitheri-body had any effect on normal lung fibroblasts (A). AMD3100 and thenegative control i-body 21H5 had no effect on any of these cell lines.

FIG. 32 shows that AM3-114-6H i-body markedly reduced ACTA2, COL1A1,COL3A1 and FN1 transcript expression in slow-IPF lung fibroblasts. Slowlung fibroblasts were plated on BME and treated with 2 mg/ml of BMEalone (open bars) and containing i-body AM3-114-6H (grey bars) orAMD3100 (black bars). RNA was extracted and qPCR analysis was performedfor pro-fibrotic transcripts. Depicted is the average transcriptexpression of alpha SMA, COL1A1, COL3A1, and FN1 in slowlung fibroblasts(n=3/group).

FIG. 33 shows the ability of i-bodies to block platelet aggregation.AM4-272, AM4-746, AM4-1121, AM3-114, AM3-523 and MAb12G5 as well as anegative control i-body (21H5) and a negative control MAB (mIgG2a) weretested for blocking SDF-1α induced platelet aggregation. Under theseconditions i-bodies AM3-114 and AM4-1121 were the most effective atblocking this aggregation.

FIG. 34 shows the effect of i-body AM4-272 on clinical scores and bodyweight of mice with induced EAE. The lines represent body weights of themice in the groups with MOG induced experimental autoimmuneencephalomyelitis (EAE) and various treatments. The bars representclinical scores of the mice in the various groups. I-body AM4-272reduces the clinical scores and prevents the bodyweight loss seen in MOGinduced EAE animals.

KEY TO SEQUENCE LISTING

SEQ ID NO 1: amino acid sequence encoding Homo sapiens NCAM domain 1SEQ ID NO: 2 amino acid sequence encoding i-body scaffold.SEQ ID NO: 3 amino acid sequence encoding Bos taurus NCAM domain 1SEQ ID NO: 4 amino acid sequence encoding Mus musculus NCAM domain 1SEQ ID NO: 5 amino acid sequence encoding Rat rattus NCAM domain 1SEQ ID NO: 6 amino acid sequence encoding Gallus gallus NCAM domain 1SEQ ID NO: 7 amino acid sequence encoding Xenopus laevis NCAM2 domain 1SEQ ID NO: 8 amino acid sequence encoding Xenopus laevis NCAM1 domain 1SEQ ID NO: 9 amino acid sequence encoding Homo sapiens NCAM2 domain 1SEQ ID NO: 10 amino acid sequence encoding Mus musculus NCAM2 domain 1SEQ ID NO: 11 amino acid sequence encoding ADCX-99SEQ ID NO: 12 amino acid sequence encoding ADCX-99 CDR1SEQ ID NO: 13 amino acid sequence encoding ADCX-99 CDR3SEQ ID NO: 14 amino acid sequence encoding ADCX-272SEQ ID NO: 15 amino acid sequence encoding ADCX-272 CDR1SEQ ID NO: 16 amino acid sequence encoding ADCX-272 CDR3SEQ ID NO: 17 amino acid sequence encoding ADCX-6SEQ ID NO: 18 amino acid sequence encoding ADCX-6 CDR1SEQ ID NO: 19 amino acid sequence encoding ADCX-6 CDR3SEQ ID NO: 20 amino acid sequence encoding ADCX-54SEQ ID NO: 21 amino acid sequence encoding ADCX-54 CDR1SEQ ID NO: 22 amino acid sequence encoding ADCX-54 CDR3SEQ ID NO: 23 amino acid sequence encoding ADCX-LSSEQ ID NO: 24 amino acid sequence encoding ADCX-LS CDR1SEQ ID NO: 25 amino acid sequence encoding ADCX-LS CDR3SEQ ID NO: 26 amino acid sequence encoding ADCX-668SEQ ID NO: 27 amino acid sequence encoding ADCX-668 CDR1SEQ ID NO: 28 amino acid sequence encoding ADCX-668 CDR3SEQ ID NO: 29 amino acid sequence encoding ADCX-306SEQ ID NO: 30 amino acid sequence encoding ADCX-306 CDR1SEQ ID NO: 31 amino acid sequence encoding ADCX-306 CDR3SEQ ID NO: 32 nucleotide sequence encoding ADCX-99SEQ ID NO: 33 nucleotide sequence encoding ADCX-272SEQ ID NO: 34 nucleotide sequence encoding ADCX-6SEQ ID NO: 35 nucleotide sequence encoding ADCX-54SEQ ID NO: 36 nucleotide sequence encoding ADCX-LSSEQ ID NO: 37 nucleotide sequence encoding ADCX-668SEQ ID NO: 38 nucleotide sequence encoding ADCX-306SEQ ID NO: 39 consensus amino acid sequence of affinity maturedi-bodies.SEQ ID NO: 40 amino acid sequence encoding AM3-114SEQ ID NO: 41 amino acid sequence encoding AM3-114 CDR1SEQ ID NO: 42 amino acid sequence encoding AM3-114 CDR3SEQ ID NO: 43 nucleotide sequence encoding AM3-114SEQ ID NO: 44 amino acid sequence encoding AM3-920SEQ ID NO: 45 amino acid sequence encoding AM3-920 CDR1SEQ ID NO: 46 amino acid sequence encoding AM3-920 CDR3SEQ ID NO: 47 nucleotide sequence encoding AM3-920SEQ ID NO: 48 amino acid sequence encoding AM4-1121SEQ ID NO: 49 amino acid sequence encoding AM4-1121 CDR1SEQ ID NO: 50 amino acid sequence encoding AM4-1121 CDR3SEQ ID NO: 51 nucleotide sequence encoding AM4-1121SEQ ID NO: 52 amino acid sequence encoding AM4-613SEQ ID NO: 53 amino acid sequence encoding AM4-613 CDR1SEQ ID NO: 54 amino acid sequence encoding AM4-613 CDR3SEQ ID NO: 55 nucleotide sequence encoding AM4-613SEQ ID NO: 56 amino acid sequence encoding AM3-523SEQ ID NO: 57 amino acid sequence encoding AM3-523 CDR1SEQ ID NO: 58 amino acid sequence encoding AM3-523 CDR3SEQ ID NO: 59 nucleotide sequence encoding AM3-523SEQ ID NO: 60 amino acid sequence encoding AM4-661SEQ ID NO: 61 amino acid sequence encoding AM4-661 CDR1SEQ ID NO: 62 amino acid sequence encoding AM4-661 CDR3SEQ ID NO: 63 nucleotide sequence encoding AM4-661SEQ ID NO: 64 amino acid sequence encoding AM3-466SEQ ID NO: 65 amino acid sequence encoding AM3-466 CDR1SEQ ID NO: 66 amino acid sequence encoding AM3-466 CDR3SEQ ID NO: 67 nucleotide sequence encoding AM3-466SEQ ID NO: 68 amino acid sequence encoding AM5-245SEQ ID NO: 69 amino acid sequence encoding AM5-245 CDR1SEQ ID NO: 70 amino acid sequence encoding AM5-245 CDR3SEQ ID NO: 71 nucleotide sequence encoding AM5-245SEQ ID NO: 72 amino acid sequence encoding AM4-272SEQ ID NO: 73 amino acid sequence encoding AM4-272 CDR1SEQ ID NO: 74 amino acid sequence encoding AM4-272 CDR3SEQ ID NO: 75 nucleotide sequence encoding AM4-272SEQ ID NO: 76 amino acid sequence encoding AM4-746SEQ ID NO: 77 amino acid sequence encoding AM4-746 CDR1SEQ ID NO: 78 amino acid sequence encoding AM4-746 CDR3SEQ ID NO: 79 nucleotide sequence encoding AM4-746SEQ ID NO: 80 amino acid sequence encoding AM3-114-Im7-FH-SA21 dualspecificity i-bodySEQ ID NO:81 nucleotide sequence encoding AM3-114-Im7-FH-SA21 dualspecificity i-bodySEQ ID NO:82 amino acid sequence encoding 21H5 i-bodySEQ ID NO:83 amino acid sequence encoding AM4-774 CDR1SEQ ID NO:84 amino acid sequence encoding AM4-774 CDR3SEQ ID NO:85 amino acid sequence encoding AM4-208 CDR1SEQ ID NO:86 amino acid sequence encoding AM4-208 CDR3SEQ ID NO:87 amino acid sequence encoding AM4-1088 CDR1SEQ ID NO:88 amino acid sequence encoding AM4-1088 CDR3SEQ ID NO:89 amino acid sequence encoding AM4-239 CDR1SEQ ID NO:90 amino acid sequence encoding AM4-239 CDR3SEQ ID NO:91 amino acid sequence encoding AM3-32 CDR1SEQ ID NO:92 amino acid sequence encoding AM3-32 CDR3SEQ ID NO:93 amino acid sequence encoding AM4-757 CDR1SEQ ID NO:94 amino acid sequence encoding AM4-757 CDR3SEQ ID NO:95 amino acid sequence encoding AM4-386 CDR1SEQ ID NO:96 amino acid sequence encoding AM4-386 CDR3SEQ ID NO:97 amino acid sequence encoding AM4-352 CDR1SEQ ID NO:98 amino acid sequence encoding AM4-352 CDR3SEQ ID NO:99 amino acid sequence encoding AM3-182 CDR1SEQ ID NO:100 amino acid sequence encoding AM3-182 CDR3SEQ ID NO:101 amino acid sequence encoding AM4-203 CDR1SEQ ID NO:102 amino acid sequence encoding AM4-203 CDR3SEQ ID NO:103 amino acid sequence encoding AM5-95 CDR1SEQ ID NO:104 amino acid sequence encoding AM5-95 CDR3SEQ ID NO:105 amino acid sequence encoding human CXCR4

DETAILED DESCRIPTION General

The term “and/or”, e.g., “X and/or Y” shall be understood to mean either“X and Y” or “X or Y” and shall be taken to provide explicit support forboth meanings or for either meaning.

Throughout this specification, unless specifically stated otherwise orthe context requires otherwise, reference to a single step, compositionof matter, group of steps or group of compositions of matter shall betaken to encompass one and a plurality (i.e. one or more) of thosesteps, compositions of matter, groups of steps or group of compositionsof matter.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications. The invention alsoincludes all of the steps, features, compositions and compounds referredto or indicated in this specification, individually or collectively, andany and all combinations or any two or more of said steps or features.

The present disclosure is not to be limited in scope by the specificembodiments described herein, which are intended for the purpose ofexemplification only. Functionally-equivalent products, compositions andmethods are clearly within the scope of the disclosure, as describedherein.

Any example herein shall be taken to apply mutatis mutandis to any otherexample unless specifically stated otherwise.

Selected Definitions

The term “comprise”, or variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated element, integeror step, or group of elements, integers or steps, but not the exclusionof any other element, integer or step, or group of elements, integers orsteps.

As used herein, the term “affinity” refers to the strength of binding ofa single molecule to its ligands and is typically expressed as theequilibrium dissociation constant (K_(D)) for the reversible binding oftwo agents. It is determined by the ratio of K_(off)/K_(on), between thei-body or CXCR4 binding polypeptide of the present disclosure and CXCR4.K_(D) and affinity are inversely related. The K_(D) value relates to theconcentration of i-body or CXCR4 binding polypeptide and so the lowerthe KD value (lower concentration), the higher the affinity of theantibody. Affinity of an i-body or CXCR4 binding polypeptide of thepresent disclosure to CXCR4 can be, for example, from about 100nanomolar (nM) to about 0.1 nM, from about 100 nM to about 1 picomolar(pM), or from about 100 nM to about 1 femtomolar (fM) or more.

As used herein, the term “binds” in reference to the interaction of aCXCR4 binding molecule or polypeptide with a target means that theinteraction is dependent upon the presence of a particular structure(e.g., an antigenic determinant or epitope) on the target. For example,a CXCR4 binding molecule or polypeptide recognizes and binds to aspecific protein structure rather than to proteins generally.

As ued herein, the term “conservative amino acid substitution” refers togrouping of amino acids on the basis of certain common properties. Afunctional way to define common properties between individual aminoacids is to analyse the normalised frequencies of amino acid changesbetween corresponding proteins of homologous organisms. According tosuch analysis, groups of amino acids may be defined where amino acidswithin a group exchange preferentially with eachother, and thereforeresemble each other most in their impact on the overall proteinstructure (Schulz G E and R H Schirmer, Principles of Protein Structure,Springer-Verlag). Examples of amino acid groups defined in this mannerinclude:

(i) charged groups, consisting of Glu, Asp, Lys, Arg and His,

(ii) aromatic groups consisting of Phe, Tyr and Trp,

(iii) nitrogen ring group consisting of His and Trp,

(iv) slightly polar group consisting of Met and Cys etc.

As used herein, the term “CXCR4-related disease or condition” shall betaken to mean disease and disorders that can be prevented and/ortreated, respectively, by suitably administering to a subject in needthereof (i.e. having the disease or disorder or at least one symptomthereof and/or at risk of attracting or developing the disease ordisorder) of either a CXCR4 binding molecule or a polypeptide orcomposition of the present disclosure and/or of a known active principleactive against CXCR4 or a biological pathway or mechanism in which CXCR4is involved. The term CXCR4 related disease or condition also includesCXCR4-mediated diseases or disorders.

As used herein, the term “homology” describes a mathematically basedcomparison of sequence similarities which is used to identify genes orproteins with similar functions or motifs. The polypeptide sequences ofthe present disclosure may be used as a “query sequence” to perform asearch against public databases to, for example, identify other familymemebers, related sequences or homologs. Such searches can be performedusing BLAST programs (Altschul et al (1990) J. Mo. Biol. 215:403-10). Toobtain gapped alignments for comparison purposes, Gapped BLAST can beutilised a described in Altschul et al (1997) Nuc Acids Res.25(17):3389-3402.

As used herein, the term “identity” means the percentage of identicalnucleotide or amino acid residues at corresponding portions in two ormore sequences when sequences are aligned to maximise sequence matching,i.e. taking into account gaps and insertions. Identity can be readilycalculated using known methods, including, but not limited to thesedescribed in Computational Molecular Biology, Lesk A M ed. OxfordUniversity Press New York, 1988; Computer Analysis of Sequence data,Part I Griffin A M and Griffin H G eds., Humana Press, New Jersey, 1994;Sequence analysis in molecular biology, von Heinje G, Academic Press,New Jersey, 1994). Methods to determine identity are designed to givethe largest match between the sequences tested. Moreover, methods todetermined identity are codified in publicly available computerprograms. Computer program methods to determine identity between twosequence include, but are not limited to, the GCG program package,BLASTP, BLASTN and FASTA. The well known Smith Waterman algorithm mayalso be used to determine identity.

As used herein, the terms “treating”, “treat” or “treatment” includeadministering a therapeutically effective amount of the polypeptide,nucleic acid molecule, conjugate or multimer of the present disclosuresufficient to reduce or eliminate at least one symptom of a specifieddisorder. In one example, the treatment involves administering atherapeutically effective amount of the polypeptide, nucleic acidmolecule, conjugate or multimer to treat or prevent a CXCR4-relateddisease or disorder. In one example, treatment also refers toprophylactic treatment.

As used herein, the terms “preventing”, “prevent” or “prevention”include administering a therapeutically effective amount of thepolypeptide, nucleic acid molecule, conjugate or multimer of the presentdisclosure sufficient to stop or hinder the development of at least onesymptom of a specified disorder.

As used herein, the term “specifically binds” or “binds specifically”shall be taken to mean a CXCR4 binding molecule or polypeptide of thedisclosure reacts or associates more frequently, more rapidly, withgreater duration and/or with greater affinity with a particular targetor cell expressing CXCR4 than it does with alternative targets or cells.More particularly, the CXCR4 binding molecule or polypeptide binds withgreater affinity to a target or cell expressing CXCR4 than it does toother chemokine receptors, for example CCR5, CXCR7 or CCR7. For example,a CXCR4 binding molecule or polypeptide that specifically binds to atarget binds that target with greater affinity (e.g. 2 fold, 10 fold, 20fold or 40 fold or 60 fold or 80 fold to 100 fold or 150 fold or 200fold greater affinity), avidity, more readily, and/or with greaterduration than it binds to other GPCRs, e.g., to other GPCRs that aresimilar in structure or sequence. A polypeptide which binds specificallyto CXCR4 may demonstrate some cross-reactivity with other chemokinereceptors or affinity related molecules but only to the extent that suchcross-reactivity does not substantially modulate a biological mechanismresponse or effect of CXCR4 binding.

As used herein, reference to a “similar” level of binding will beunderstood to mean that a CXCR4 binding molecule or polypeptide binds toa target at a level within about 30% or 25% or 20% of the level at whichit binds to another target. This term can also mean that one bindingmolecule or polypeptide binds to a target at a level within about 30% or25% or 20% of the level at which another binding molecule or polypeptidebinds to the same target.

The term “substantially” as used herein in the context of binding,refers to a polypeptide that binds to CXCR4 at a level within about 15%,or 10% or 5% of the level at which it binds to another target. This termcan also mean that one binding molecule or polypeptide binds to a targetat a level within about 5% or 4% or 3% of the level at which anotherbinding molecule or polypeptide binds to the same target.

The term “random loop sequence” as used herein refers to a portion of apeptide sequence that extends either from or between a β-strandconformation or β-strand conformations of an intermediate (I-SET)domain. Loop regions are typically free of extended β-strandconformations. Loop region 4 is analogous to a conventional CDR1 loop.Loop region 8 is analogous to a conventional CDR3 loop.

As used herein, the term “complementarity determining regions” (syn.CDRs; i.e., CDR1, CDR2, and CDR3) refers to the amino acid residueswithin an immunoglopbulin superfamily domain, the presence of which aremajor contributors to specific antigen binding.

The term “scaffold” or “i-body scaffold” as used herein is intended torefer to the sequence represented by the scaffold regions of the i-SEThuman NCAM1 Immunoglobulin (Ig) domain 1 (SEQ ID NO:1) defined by aminoacids 1 to 26, 33 to 79 and 88 to 97.

The term “isolated” as used herein in the context of isolatedpolypeptide or isolated binding polypeptide refers to a protein orrecombinant or synthetic origin or some combination thereof, which byvirtue of its origin or source of derivation the protein is notassociated with proteins found in nature, is free of other proteins fromthe same source, is expressed by a cell from a different species or doesnot occur in nature.

The term “therapeutically effective amount” refers to an amount oftherapeutic agent that when administered alone or in combination withanother therapeutic agent to a cell, tissue or subject is effective toprevent or ameliorate the disease condition or the progression of thedisease.

The term “peptide mimetic” or “peptidomimetic” means a peptide-likemolecule that is able to serve as a model for a peptide substrate uponwhich it is structurally based. Such peptidomimetics include chemicallymodified peptides, peptide-like molecules containing non-naturallyoccurring amino acids, and peptoids, which are peptide-like moleculesresulting from oligomeric assembly of N-substituted glycines (see, forexample, Goodman and Ro, Peptidomimetics for Drug Design, in BURGER'SMEDICINAL CHEMISTRY AND DRUG DISCOVERY Vol. 1 (ed. M. E. Wolff; JohnWiley & Sons 1995), pages 803-861).

A variety of peptide mimetics are known in the art including, forexample, peptide-like molecules which contain a constrained amino acid,a non-peptide component that mimics peptide secondary structure, or anamide bond isostere. A peptide mimetic that contains a constrained,non-naturally occurring amino acid can include, for example, anα-methylated amino acid; an α,α-dialkyl-glycine or α-aminocycloalkanecarboxylic acid; an Nα-Cα cyclized amino acid; an Nα-methylated aminoacid; a β- or γ-amino cycloalkane carboxylic acid; an α,β-unsaturatedamino acid; a β,β-dimethyl or β-methyl amino acid; aδ-substituted-2,3-methano amino acid; an NCδ or Cα-Cδ cyclized aminoacid; or a substituted proline or another amino acid mimetic.

In addition, a peptide mimetic which mimics peptide secondary structurecan contain, for example, a nonpeptidic β-turn mimic; γ-turn mimic;mimic of β-sheet structure; or mimic of helical structure, each of whichis well known in the art. A peptide mimetic also can be a peptide-likemolecule which contains, for example, an amide bond isostere such as aretro-inverso modification; reduced amide bond; methylenethioether ormethylenesulfoxide bond; methylene ether bond; ethylene bond; thioamidebond; trans-olefin or fluoroolefin bond; 1,5-disubstituted tetrazolering; ketomethylene or fluoroketomethylene bond or another amideisostere. One skilled in the art understands that these and otherpeptidomimetic components are encompassed within the meaning of the term“peptide imetic” as used herein. The term “polypeptide” or “peptide”shall include peptidomimetics unless expressly indicated otherwise.

I-Body Scaffold and CXCR4 Binding Molecules

The present disclosure provides a binding polypeptide (or “i-body”),which comprises a scaffold with modified CDR1 and CDR3 regions. In oneexample the scaffold region comprises Domain 1 of human NCAM1 as shownin SEQ ID NO:1 or a related domain sequence that has at least 45%identity thereto or at least 75% homology excluding CDR1 and CDR3regions as highlighted.

NCAM (or Neural Cell Adhesion Molecule) is a glycoprotein of the I-SETdomains or intermediate-set domains from the Immunoglobulin (Ig)superfamily. The extracellular domain of NCAM consists of fiveimmunoglobulin-like (Ig) domains followed by two fibronectin type III(FNIII) domains.

Related domain sequences include SEQ ID NO's 3, 4, 5, 6 and 8 which showcow, mouse, rat, chicken and frog NCAM 1 domain sequences respectivelyand SEQ ID NO's 7, 9 and 10 which show frog, human and mouse NCAM 2domain sequences respectively.

The sequence identity between these related domains is as follows:

NCBI REF Score E value P13591.3|NCAM1_HUMAN RecName: NCAM 200 5e−60Identity (100%) SEQ ID NO: 1 P31836.1|NCAM1_BOVIN RecName: NCAM 1976e−59 Identity (98%) SEQ ID NO: 3  P13595.3|NCAM1_MOUSE RecName: NCAM195 2e−57 Identity (95%) SEQ ID NO: 4  P13596.1|NCAM1_RAT RecName: NCAM192 3e−57 Identity (95%) SEQ ID NO: 5  P13590.3|NCAM1_CHICK RecName:NCAM 175 2e−50 Identity (89%) SEQ ID NO: 6  P36335.1|NCA12_XENLARecName: NCAM 130 1e−34 Identity (68%) SEQ ID NO: 7 P16170.1|NCA11_XENLA RecName: NCAM 130 1e−34 Identity (68%) SEQ ID NO:8  O15394.2|NCAM2_HUMAN RecName: NCAM 87.8 8e−20 Identity (51%) SEQ IDNO: 9  O35136.1|NCAM2_MOUSE RecName: NCAM 86.3 3e−19 Identity (47%) SEQID NO: 10The sequence homology between these related domains is as follows:

sp|P13591.3|NCAM1_HUMAN RecName: NCAM Sequence homology (100%) SEQ IDNO: 1 sp|P31836.1|NCAM1_BOVIN RecName: NCAM Sequence homology (100%) SEQID NO: 3 sp|P13595.3|NCAM1_MOUSE RecName: NCAM Sequence homology (99%)SEQ ID NO: 4  sp|P13596.1|NCAM1_RAT RecName: NCAM Sequence homology(99%) SEQ ID NO: 5  sp|P13590.3|NCAM1_CHICK RecName: NCAM Sequencehomology (98%) SEQ ID NO: 6  sp|P36335.1|NCA12_XENLA RecName: NCAMSequence homology (89%) SEQ ID NO: 7  sp|P16170.1|NCA11_XENLA RecName:NCAM Sequence homology (89%) SEQ ID NO: 8  sp|O15394.2|NCAM2_HUMANRecName: NCAM Sequence homology (74%) SEQ ID NO: 9 sp|O35136.1|NCAM2_MOUSE RecName: NCAM Sequence homology (74%) SEQ ID NO:10

Domain 1 of human NCAM has been produced as a recombinant polypeptide ina bacterial expression system (Frei et al. (1992) J. Cell Biol.118:177-194).

The present disclosure describes modifications introduced into an i-bodyscaffold in the CDR1 and/or CDR3 regions, which have been shown to alterthe binding properties of the domain (or “i-body”). In particular, theinventors have developed modified i-body amino acids and polypeptideswhich surprisingly are able to bind to CXCR4 with high affinity andspecificity and inhibit or reduce CXCR4-induced cell migration. Inparticular, the CXCR4 binding polypeptides or i-bodies of the presentdisclosure are useful in inhibiting cancer metastasis, anti-inflammatoryand fibrosis related diseases.

Accordingly the present disclosure provides a number of polypeptideswhich bind to CXCR4 which comprise the i-body scaffold acid sequence,wherein the CDR1 or CDR3 region of the i-body scaffold have beenmodified and wherein the molecule binds to human CXCR4 with an affinityof less than 50 uM, less than 40 μM, less than 20 μM, less than 10 uM,less than 1 uM, less than 700 nM, less than 600 nM, less than 500 nM,less than 400 nM, less than 300 nM, less than 200 nM, less than 100 nM,less than 50 nM, less than 10 nM, or less than 5 nM or less than 1 nM.

In one embodiment the entire CDR1 and/or CDR3 regions of the polypeptideare replaced with a random loop sequence.

For example, the CDR1 loop region of the polypeptide may be replacedwith a loop region having the sequence as shown in SEQ ID NO: 12, SEQ IDNO:15, SEQ ID NO:18, SEQ ID NO:21, SEQ ID NO:24, SEQ ID NO: 27, SEQ IDNO: 30, SEQ ID NO: 41, SEQ ID NO: 45, SEQ ID NO: 49, SEQ ID NO: 53, SEQID NO: 57, SEQ ID NO:61, SEQ ID NO:65, SEQ ID NO:69, SEQ ID NO:73, orSEQ ID NO:77 or a sequence having at least 50% identity thereto.

For example, the CDR1 loop region of the polypeptide may be replacedwith a loop region having the sequence as shown in SEQ ID NO: 12, SEQ IDNO:15, SEQ ID NO:18, SEQ ID NO:21, SEQ ID NO:24, SEQ ID NO: 27, SEQ IDNO: 30, SEQ ID NO: 41, SEQ ID NO: 45, SEQ ID NO: 49, SEQ ID NO: 53, SEQID NO: 57, SEQ ID NO: 61, SEQ ID NO: 65, SEQ ID NO: 69, SEQ ID NO: 73,or SEQ ID NO: 77 or a sequence having at least 50% homology thereto.

In another example, the CDR3 loop region of the polypeptide may bereplaced with a loop region having the sequence as shown in SEQ ID NO:13, SEQ ID NO: 16, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQ IDNO: 28, SEQ ID NO: 31, SEQ ID NO: 42, SEQ ID NO: 46, SEQ ID NO: 50, SEQID NO: 54, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 66, SEQ ID NO: 70,SEQ ID NO: 74, or SEQ ID NO: 78, a sequence having at least 70% identitythereto.

In another example, the CDR3 loop region of the polypeptide may bereplaced with a loop region having the sequence as shown in SEQ ID NO:13, SEQ ID NO: 16, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQ IDNO: 28, SEQ ID NO: 31, SEQ ID NO: 42, SEQ ID NO: 46, SEQ ID NO: 50, SEQID NO: 54, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 66, SEQ ID NO:70,SEQ ID NO: 74, or SEQ ID NO: 78 a sequence having at least 70% homologythereto.

In one example the polypeptide comprises a sequence that has at least80% identity, at least 90% identity, or at least 95% identity, or atleast 97% identity, or at least 98% identity, or at least 99% identityto identity to SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO:20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29, SEQ ID NO: 40, SEQ IDNO: 44, SEQ ID NO: 48, SEQ ID NO: 52 or SEQ ID NO: 56, SEQ ID NO:60, SEQID NO: 64, SEQ ID NO: 68, SEQ ID NO: 72, or SEQ ID NO: 76.

In one example the polypeptide comprises a sequence that has at least80% homology, at least 90% homology, or at least 95% homology, or atleast 97% homology, or at least 98% homology, or at least 99% homologyto SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ IDNO: 23, SEQ ID NO: 26, SEQ ID NO: 29, SEQ ID NO: 40, SEQ ID NO: 44, SEQID NO: 48, SEQ ID NO: 52 or SEQ ID NO: 56, SEQ ID NO:60, SEQ ID NO: 64,SEQ ID NO: 68, SEQ ID NO: 72, or SEQ ID NO: 76.

In one example the polypeptide comprises or consists of SEQ ID NO: 11,SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO:26, SEQ ID NO: 29, SEQ ID NO: 40, SEQ ID NO: 44, SEQ ID NO: 48, SEQ IDNO: 52 or SEQ ID NO: 56, SEQ ID NO:60, SEQ ID NO: 64, SEQ ID NO: 68, SEQID NO: 72, or SEQ ID NO: 76.

In one example the polypeptide comprises or consists of SEQ ID NO: 11comprising one, two, three, four, five, six, seven, eight, nine or tenamino acid substitutions.

In one example the polypeptide comprises or consists of SEQ ID NO: 11.

The present disclosure also provides a nucleic acid molecule encoding apolypeptide described herein.

In one example the nucleic acid molecule comprises a sequence that hasat least 80% identity, at least 90% identity, or at least 95% identity,or at least 97% identity, or at least 98% identity, or at least 99%identity or 100% identity to any one of SEQ ID NO: 32, SEQ ID NO: 33,SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO:38, SEQ ID NO: 43, SEQ ID NO: 47, SEQ ID NO: 51, SEQ ID NO: 55, SEQ IDNO: 59, SEQ ID NO: 63, SEQ ID NO: 67, SEQ ID NO: 71, SEQ ID NO: 75, orSEQ ID NO: 79.

In one example the nucleic acid molecule comprises a sequence that hasat least 80% homology, at least 90% homology, or at least 95% homology,or at least 97% homology, or at least 98% homology, or at least 99%homology or 100% homology to any one of SEQ ID NO: 32, SEQ ID NO: 33,SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO:38, SEQ ID NO: 43, SEQ ID NO: 47, SEQ ID NO: 51, SEQ ID NO: 55, SEQ IDNO: 59, SEQ ID NO: 63, SEQ ID NO: 67, SEQ ID NO: 71, SEQ ID NO: 75, orSEQ ID NO: 79.

The % identity of a polypeptide or polynucleotide is determined by GAP(Needleman and Wunsch, 1970) analysis (GCG program) with a gap creationpenalty=5, and a gap extension penalty=0.3. The query sequence is atleast 50 residues in length, and the GAP analysis aligns the twosequences over a region of at least 50 residues. For example, the querysequence is at least 100 residues in length and the GAP analysis alignsthe two sequences over a region of at least 100 residues. In oneexample, the two sequences are aligned over their entire length.

For purposes of the present disclosure, alignments of sequences andcalculation of homology scores are done using a Needleman-Wunschalignment (i.e. global alignment), useful for both protein and DNAalignments. The default scoring matrices BLOSUM50 and the identitymatrix are used for protein and DNA alignments respectively. The penaltyfor the first residue in a gap is −12 for proteins and −16 for DNA,white the penalty for additional residues in a gap is −2 for proteinsand −4 for DNA. Alignment is from the FASTA package version v20u6 (W. R.Pearson and D. J. Lipman (1988), “Improved Tools for Biological SequenceAnalysis”, PNAS 85:2444-2448, and W. R. Pearson (1990) “Rapid andSensitive Sequence Comparison with FASTP and FASTA”, Methods inEnzymology, 183:63-98).

The present disclosure contemplates variant forms of binding protein ofthe disclosure. For example, such a variant binding protein comprisesone or more conservative amino acid substitutions compared to a sequenceset forth herein. In some examples, the binding protein comprises 10 orfewer, e.g., 9 or 8 or 7 or 6 or 5 or 4 or 3 or 2 or 1 conservativeamino acid substitutions. A “conservative amino acid substitution” isone in which the amino acid residue is replaced with an amino acidresidue having a similar side chain and/or hydropathicity and/orhydrophilicity.

Families of amino acid residues having similar side chains have beendefined in the art, including basic side chains (e.g., lysine, arginine,histidine), acidic side chains (e.g., aspartic acid, glutamic acid),uncharged polar side chains (e.g., glycine, asparagine, glutamine,serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g.,alanine, valine, leucine, isoleucine, proline, phenylalanine,methionine, tryptophan), β-branched side chains (e.g., threonine,valine, isoleucine) and aromatic side chains (e.g., tyrosine,phenylalanine, tryptophan, histidine). Hydropathic indices aredescribed, for example in Kyte and Doolittle (1982) and hydrophylicindices are described in, e.g., U.S. Pat. No. 4,554,101.

The present disclosure also contemplates non-conservative amino acidchanges. For example, of particular interest are substitutions ofcharged amino acids with another charged amino acid and with neutral orpositively charged amino acids. In some examples, the binding proteincomprises 10 or fewer, e.g., 9 or 8 or 7 or 6 or 5 or 4 or 3 or 2 or 1non-conservative amino acid substitutions.

A variant form of a CXCR4 binding protein described herein retains theability to bind to CXCR4. Methods for determining specific binding toCXCR4 are described herein.

Affinity Maturation

In a further example, a polypeptide of the disclosure is affinitymatured to produce an i-body capable of binding to CXCR4 with increasedaffinity, specificity or activity or to produce an i-body with increasedexpression or solubility. For example, the sequence encoding thepolypeptide of the disclosure is mutated such that one or more aminoacid substitutions is introduced. The resulting variant polypeptide isthen screened for binding to CXCR4, e.g., in a competitive assay,screened for increase in specificity to other chemokine receptors (forexample CCR10, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, CX3CR1,CXCR1, CXCR2, CXCR3, CXCR5, CXCR6, CXCR7, CCR1, XCR1; see FIG. 9), orscreened for increase in expression or increase in solubility (see FIG.7) or screened via affinity assays as described below for increases inaffinity to CXCR4.

There are several protocols for affinity maturation of polypeptides andproteins. These include DNA shuffling (Stemmer Proc Natl Acad Sci USA.(1994); 91(22):10747-10751), error-prone PCR (Hawkins et al. (1992) J.Mol. Biol., 226; 889-896 and Henderson et al. (2007) Structure15:1452-66) and bacterial mutator cells (Irving et al. (1996)Immunotechnology 2:127-43.3) that randomise the whole scaffold, as wellas more targeted methods such as doped oligonucleotide mutagenesis(Hermes et al. (1989) Gene, 84; 143-1514). Ribosome display coupled witherror-prone RNA dependent RNA polymerase from Qbeta bacteriophage hasalso been used to affinity mature single domains, binding proteins andpolypeptides (Kopsidas et al, (2006) Immunology Letters 107 163-168).

The polypeptides according to the disclosure may be soluble secretedproteins or may be presented as a fusion protein on the surface of acell, or particle (e.g., a phage or other virus, a ribosome or a spore).Exemplary phage display methods are described, for example, in U.S. Pat.No. 5,821,047; U.S. Pat. No. 6,248,516 and U.S. Pat. No. 6,190,908.Phage display particles produced using these methods are then screenedto identify a displayed binding protein having a conformation sufficientfor binding to CXCR4 or an improved binder to CXCR4.

Apparent affinities can be determined by methods such as an enzymelinked immunosorbent assay (ELISA) or any other technique familiar toone of skill in the art. Avidities can be determined by methods such asa Scatchard analysis or any other technique familiar to one of skill inthe art. Another technique for measuring apparent binding affinityfamiliar to those of skill in the art is a surface plasmon resonancetechnique (analyzed on a BIACORE 2000 system) (Liljeblad, et al., Glyco.J. 2000, 17:323-329). Standard measurements and traditional bindingassays are described by Heeley, R. P, Endocr. Res. 2002, 28:217-229.

In one example, an affinity matured i-body of the present disclosurespecifically binds to human CXCR4 with a greater binding affinity (e.g.at least about 5 times, at least about 10 times, at least about 50times, at least about 100 times, at least about 500 times, or at leastabout 1000 times greater) than the binding affinity of the non-affinitymatured i-body.

Protein Production

In one example, a polypeptide of the disclosure is produced by culturinga cell line, e.g., an E. Coli cell line under conditions sufficient toproduce the protein, e.g., as described herein and/or as is known in theart.

Recombinant Expression

In the case of a recombinant protein, nucleic acid encoding same isplaced into one or more expression constructs, e.g., expressionvector(s), which is/are then transfected into host cells, such as cellsthat can produce a disulphide bridge or bond, such as bacterial cellsincluding E. coli cells, yeast cells, insect cells, or mammalian cells.Exemplary mammalian cells include simian COS cells, Chinese HamsterOvary (CHO) cells, or myeloma cells that do not otherwise produceimmunoglobulin protein. Exemplary bacterial cells include BL21(DE3),BL21(DE3)-pLysS, Tuner, Tuner pLysS, Origami, Origami B, Origami BpLysS, Rosetta, AD494, HMS174 which are all available form Novagen.

Molecular cloning techniques to achieve these ends are known in the artand described, for example in Ausubel F M (1987) Current Protocols inMolecular Biology. New York. N.Y., John Wiley & Sons or Sambrook,Fritsch and Maniatis Molecular Cloning: a laboratory manual Cold SpringHarbor N.Y. Cold Spring Harbor Laboratory Press. A wide variety ofcloning and in vitro amplification methods are suitable for theconstruction of recombinant nucleic acids.

Following isolation, the nucleic acid encoding a protein of thedisclosure is inserted into an expression construct or replicable vectorfor further cloning (amplification of the DNA) or for expression in acell-free system or in cells. For example, the nucleic acid is operablylinked to a promoter.

As used herein, the term “promoter” is to be taken in its broadestcontext and includes the transcriptional regulatory sequences of agenomic gene, including the TATA box or initiator element, which isrequired for accurate transcription initiation, with or withoutadditional regulatory elements (e.g., upstream activating sequences,transcription factor binding sites, enhancers and silencers) that alterexpression of a nucleic acid, e.g., in response to a developmentaland/or external stimulus, or in a tissue specific manner. In the presentcontext, the term “promoter” is also used to describe a recombinant,synthetic or fusion nucleic acid, or derivative which confers, activatesor enhances the expression of a nucleic acid to which it is operablylinked. Exemplary promoters can contain additional copies of one or morespecific regulatory elements to further enhance expression and/or alterthe spatial expression and/or temporal expression of said nucleic acid.

As used herein, the term “operably linked to” means positioning apromoter relative to a nucleic acid such that expression of the nucleicacid is controlled by the promoter.

Cell free expression systems are also contemplated by the presentdisclosure. For example, a nucleic acid encoding a CXCR4 bindingpolypeptide is operably linked to a suitable promoter, e.g., a T7, T5 orSP6 promoter, and the resulting expression construct exposed toconditions sufficient for transcription and translation. Typicalexpression vectors for in vitro expression or cell-free expression havebeen described and include, but are not limited to the TNT T7 and TNT T3systems (Promega), the pEXP1-DEST and pEXP2-DEST vectors (Invitrogen).

Many vectors for expression in cells are available. The vectorcomponents generally include, but are not limited to, one or more of thefollowing: a signal sequence, a sequence encoding a polypeptide of thepresent disclosure (e.g., derived from the information provided herein),an enhancer element, a promoter, and a transcription terminationsequence. The skilled artisan will be aware of suitable sequences forexpression of a protein. Vectors can be plasmids, viral e.g. phage orphagemid as appropriate. Many known techniques and protocols formanipulation of nucleic acid, for example, in the preparation of nucleicacid constructs, mutagenesis, introduction of DNA into cells and geneexpression and analysis of protein are described in for example, AusubelF M (1987) Current Protocols in Molecular Biology. New York. N.Y., JohnWiley & Sons. A wide variety of host/expression vector combinations canbe employed in expressing the i-body DNA segues of the disclosure.Useful expression vectors, for example, can consist of segments ofchromosomal, non-chromosomal and synthetic DNA sequences. Suitablevectors include derivatives of SV40 and known bacterial plasmids, e.g.,E. coli plasmids col El, Perl, Pbr322, Pmb9 and their derivatives,plasmids such as RP4; phage DNAs, e.g., the numerous derivatives ofphage\e.g., NM989, and other phage DNA, e.g., M13 and filamentous singlestranded phage DNA; yeast plasmids such as the 2u plasmid or derivativesthereof; vectors useful in eukaryotic cells, such as vectors useful ininsect or mammalian cells; vectors derived from combinations of plasmidsand phage DNAs, such as plasmids that have been modified to employ phageDNA or other expression control sequences; and the like.

Exemplary signal sequences include prokaryotic secretion signals (e.g.,DsbA, pelB, alkaline phosphatase, penicillinase, Ipp, or heat-stableenterotoxin II), yeast secretion signals (e.g., invertase leader, αfactor leader, or acid phosphatase leader) or mammalian secretionsignals (e.g., herpes simplex gD signal).

Exemplary leader peptides include those active in prokaryotes (such asPeIB, OmpA, Pill, DsbA, TorT, TolB, phoA promoter, β-lactamase andlactose promoter systems, alkaline phosphatase, a tryptophan (trp)promoter system, and hybrid promoters such as the tac promoter).

Suitable bacterial promoters include the E. coli lacI and lacZpromoters, the T3 and T7, T5 promoters, the gpt promoter, the lambda PRand PL promoters and the trp promoter. Eukaryotic promoters include theCMV immediate early promoter, the HSV thymidine kinase promoter, theearly and late SV40 promoters, the promoters of retroviral LTRs, such asthose of the Rous sarcoma virus (RSV), and metallothionein promoters,such as the mouse metallothionein-I promoter.

Exemplary promoters active in mammalian cells include cytomegalovirusimmediate early promoter (CMV-IE), human elongation factor 1-α promoter(EF1), small nuclear RNA promoters (U1a and U1b), α-myosin heavy chainpromoter, Simian virus 40 promoter (SV40), Rous sarcoma virus promoter(RSV), Adenovirus major late promoter, β-actin promoter; hybridregulatory element comprising a CMV enhancer/β-actin promoter or animmunoglobulin promoter or active fragment thereof. Examples of usefulmammalian host cell lines are monkey kidney CV1 line transformed by SV40(COS-7, AUSTRALIAN CELL BANK CRL 1651); human embryonic kidney line (293or 293 cells subcloned for growth in suspension culture; baby hamsterkidney cells (BHK, AUSTRALIAN CELL BANK CCL 10); or Chinese hamsterovary cells (CHO).

Typical promoters suitable for expression in yeast cells such as forexample a yeast cell selected from the group comprising Pichia pastoris,Saccharomyces cerevisiae and S. pombe, include, but are not limited to,the ADH1 promoter, the GAL1 promoter, the GAL4 promoter, the CUP1promoter, the PHOS promoter, the nmt promoter, the RPR1 promoter, or theTEF1 promoter.

Means for introducing the isolated nucleic acid molecule or a geneconstruct comprising same into a cell for expression are known to thoseskilled in the art. The technique used for a given cell depends on theknown successful techniques. Means for introducing recombinant DNA intocells include microinjection, transfection mediated by DEAE-dextran,transfection mediated by liposomes such as by using lipofectamine(Gibco, Md., USA) and/or cellfectin (Gibco, Md., USA), PEG-mediated DNAuptake, electroporation, viral transduction (e.g., using a lentivirus)and microparticle bombardment such as by using DNA-coated tungsten orgold particles (Agracetus Inc., WI, USA) amongst others.

In some cases it is useful to express a protein, polypeptide or peptidein insoluble form, particularly when the polypeptide of interest israther short, normally soluble, and/or subject to proteolyticdegradation within the host cell. Production of the protein in insolubleform both facilitates simple recovery and protects the polypeptide fromthe undesirable proteolytic degradation. One means to produce thepolypeptide in insoluble form is to recombinantly produce thepolypeptide as part of an insoluble fusion protein by including in thefusion construct at least one peptide tag (i.e., an inclusion body tag)that induces inclusion body formation. Typically, the fusion protein isdesigned to include at least one cleavable peptide linker so that thepolypeptide of interest can be subsequently recovered from the fusionprotein. The fusion protein may be designed to include a plurality ofinclusion body tags, cleavable peptide linkers, and regions encoding thepolypeptide of interest.

Fusion proteins comprising a peptide tag that facilitate the expressionof insoluble proteins are well known in the art. Typically, the tagportion of the chimeric or fusion protein is large, increasing thelikelihood that the fusion protein will be insoluble. Example of largepeptide tags typically used include, but are not limited tochloramphenicol acetyltransferase (Dykes et al., Eur. J. Biochem.,174:411 (1988), .beta.-galactosidase (Schellenberger et al., Int. J.Peptide Protein Res., 41:326 (1993); Shen et al., Proc. Nat. Acad. Sci.USA 281:4627 (1984); and Kempe et al., Gene, 39:239 (1985)),glutathione-S-transferase (Ray et al., Bio/Technology, 11:64 (1993) andHancock et al. (WO94/04688)), the N-terminus of L-ribulokinase (U.S.Pat. No. 5,206,154 and Lai et al., Antimicrob. Agents & Chemo., 37:1614(1993), bacteriophage T4 gp55 protein (Gramm et al., Bio/Technology,12:1017 (1994), bacterial ketosteroid isomerase protein (Kuliopulos etal., J. Am. Chem. Soc. 116:4599 (1994), ubiquitin (Pilon et al.,Biotechnol. Prog., 13:374-79 (1997), bovine prochymosin (Naught et al.,Biotechnol. Bioengineer. 57:55-61 (1998), andbactericidal/permeability-increasing protein (“BPI”; Better, M. D. andGavit, P D., U.S. Pat. No. 6,242,219). The art is replete with specificexamples of this technology, see for example U.S. Pat. No. 6,613,548,describing fusion protein of a proteinaceous tag and a soluble proteinand subsequent purification from cell lysate; U.S. Pat. No. 6,037,145,teaching a tag that protects the expressed chimeric protein from aspecific protease; U.S. Pat. No. 5,648,244, teaching the synthesis of afusion protein having a tag and a cleavable linker for facilepurification of the desired protein; and U.S. Pat. No. 5,215,896; U.S.Pat. No. 5,302,526; U.S. Pat. No. 5,330,902; and US 2005221444,describing fusion tags containing amino acid compositions specificallydesigned to increase insolubility of the chimeric protein or peptide.

Shorter inclusion body tags have recently been developed from the Zeamays zein protein (U.S. patent application Ser. No. 11/641,936), theDaucus carota cystatin (U.S. patent application Ser. No. 11/641,273),and an amyloid-like hypothetical protein from Caenorhabditis elegans(U.S. patent application Ser. No. 11/516,362; each hereby incorporatedby reference in their entirety) The use of short inclusion body tagsincreases the yield of the target peptide produced within therecombinant host cell.

Also provided herein is a recombinant host cell which comprises one ormore polynucleotide constructs. A polynucleotide encoding an i-body ofthe present disclosure is encompassed herein as are methods ofproduction of i-bodies which method comprises expression from apolynucleotide. Expression can be achieved, for example, by culturingunder appropriate conditions recombinant host cells containing thepolynucleotide.

The host cells used to produce the binding molecule or poypeptide ofthis disclosure may be cultured in a variety of media, depending on thecell type used. Commercially available media such as Ham's FI0 (Sigma),Minimal Essential Medium ((MEM), (Sigma), RPMI-1640 (Sigma), andDulbecco's Modified Eagle's Medium ((DMEM), Sigma) are suitable forculturing mammalian cells. Media for culturing other cell typesdiscussed herein are known in the art.

It will be understood that not all vectors, expression control sequencesand hosts will function equally well to express the DNA sequences.Neither will all hosts function equally well with the same expressionsystem. However, one skilled in the art will be able to select theproper vectors, expression control sequences, and hosts without undueexperimentation to accomplish the desired expression without departingfrom the scope of this application. For example, in selecting a vector,the host must be considered because the vector must function in it. Thevector's copy number, the ability to control that copy number, and theexpression of any other proteins encoded by the vector, such asantibiotic markers, will also be considered.

The present disclosure also provides a host cell containing one or morepolynucleotides as disclosed herein. The present disclosure alsoprovides a method of introducing such one or more polynucleotides into ahost cell by any suitable technique as described above.

Once the polynucleotide has been introduced into the host cell,expression of the polynucleotide can occur, e.g. by culturing host cellsunder conditions for expression of one or more polypeptides from one ormore polynucleotides.

A polynucleotide encoding an i-body of the present disclosure can beprepared recombinantly/synthetically, in addition to, or rather thancloning. The polynucleotide can be designed with the appropriate codonsfor the CXCR4 binding polypeptide. In general, one will select preferredcodons for an intended host if the sequence will be used for expression.The complete polynucleotide can be assembled from overlappingoligonucleotides prepared by standard methods and assembled into acomplete coding sequence. See, e.g., Edge, Nature, 292:756 (1981);Nambair et al., Science, 223:1299 (1984); Jay et al., J. Biol. Chem.,259:6311 (1984).

Isolation of Proteins

A CXCR4 binding molecule or polypeptide or i-body of the presentdisclosure can be isolated or purified.

Methods for purifying a polypeptide of the disclosure are known in theart and/or described herein.

When using recombinant techniques, the polypeptide of the disclosure canbe produced intracellularly, in the periplasmic space, or directlysecreted into the medium. If the protein is produced intracellularly, asa first step, the particulate debris, either host cells or lysedfragments, is removed, for example, by centrifugation orultrafiltration. Where the protein is secreted into the medium,supernatants from such expression systems can be first concentratedusing a commercially available protein concentration filter, forexample, an Amicon or Millipore Pellicon ultrafiltration unit. Aprotease inhibitor such as PMSF may be included in any of the foregoingsteps to inhibit proteolysis and antibiotics may be included to preventthe growth of adventitious contaminants.

The protein prepared from the cells can be purified using, for example,ion exchange, hydroxyapatite chromatography, hydrophobic interactionchromatography, gel electrophoresis, dialysis, affinity chromatography(e.g., protein A affinity chromatography or protein G chromatography),heat, or any combination of the foregoing. These methods are known inthe art and described, for example in WO99/57134.

The skilled artisan will also be aware that a polypeptide of thedisclosure can be modified to include a tag to facilitate purificationor detection, e.g., a poly-histidine tag, e.g., a hexa-histidine tag, ora influenza virus hemagglutinin (HA) tag, or a Simian Virus 5 (V5) tag,or a FLAG tag, or a glutathione S-transferase (GST) tag. For example,the tag is a hexa-his tag. The resulting protein is then purified usingmethods known in the art, such as, affinity purification. For example, aprotein comprising a hexa-his tag is purified by contacting a samplecomprising the protein with nickel-nitrilotriacetic acid (Ni-NTA) thatspecifically binds a hexa-his tag immobilized on a solid or semi-solidsupport, washing the sample to remove unbound protein, and subsequentlyeluting the bound protein. Alternatively, or in addition a polypeptide,ligand or antibody that binds to a tag is used in an affinitypurification method.

Conjugates

The present disclosure also provides conjugates of CXCR4 bindingmolecules or polypeptides described herein. Examples of compounds towhich a polypeptide of the present disclosure can be conjugated areselected from the group consisting of a radioisotope, a detectablelabel, a therapeutic compound, a colloid, a toxin, a nucleic acid, apeptide, a protein, a compound that increases the half life of theprotein in a subject and mixtures thereof.

Exemplary therapeutic agents include, but are not limited to ananti-angiogenic agent, an anti-neovascularization and/or othervascularization agent, an anti-proliferative agent, a pro-apoptoticagent, a chemotherapeutic agent, anti-mitotic agents (eg anti-mitoticagent Auristatin, (MMAF/MMAE as per Angew. Chem. Int. Ed. 2014, 53, 1-6)or a therapeutic nucleic acid.

A toxin includes any agent that is detrimental to (e.g., kills) cells.For a description of these classes of drugs, which are known in the art,and their mechanisms of action, see Goodman et al., (1990). Additionaltechniques relevant to the preparation of antibody immunotoxinconjugates are provided in for instance in U.S. Pat. No. 5,194,594 andmay be utilised in the present disclosure. Exemplary toxins includediphtheria A chain, nonbinding active fragments of diphtheria toxin,exotoxin A chain (from Pseudomonas aeruginosa), ricin A chain, abrin Achain, modeccin A chain, alpha-sarcin, Aleurites fordii proteins,dianthin proteins, Phytolaca americana proteins (PAPI, PAPII, andPAP-S), momordica charantia inhibitor, curcin, crotin, sapaonariaofficinalis inhibitor, gelonin, mitogellin, restrictocin, phenomycin,enomycin and the tricothecenes. See, for example, WO93/21232.

In some examples, the CXCR4 binding molecules or polypeptides ori-bodies can be covalently or non-covalently coupled to a cytotoxin orother cell proliferation inhibiting compound, in order to localisedelivery of that agent to a tumour cell. For instance, the agent can beselected from the group consisting agents, enzyme inhibitors,proliferation inhibitors, lytic agents, DNA or RNA synthesis inhibitors,membrane permeability modifiers, DNA metabolites, dichloroethylsulfidederivatives, protein production inhibitors, ribosome inhibitors,inducers of apoptosis, and neurotoxins.

Suitable chemotherapeutic agents for forming immunoconjugates of thepresent disclosure include taxol, cytochalasin B, gramicidin D, ethidiumbromide, emetine, mitomycin, etoposide, tenoposide, vincristine,vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracindione, mitoxantrone, mithramycin, actinomycin D, 1 de-hydrotestosterone,glucocorticoids, procaine, tetracaine, lidocaine, propranolol, andpuromycin, antimetabolites (such as methotrexate, 6-mercaptopurine, 6thioguanine, cytarabine, fludarabin, 5-fluorouracil, decarbazine,hydroxyurea, asparaginase, gemcitabine, cladribine), alkylating agents(such as mechlorethamine, thioepa, chlorambucil, melphalan, carmustine(BSNU), lomustine (CCNU), cyclophosphamide, busulfan, dibromomannitol,streptozotocin, dacarbazine (DTIC), procarbazine, mitomycin C, cisplatinand other platinum derivatives, such as carboplatin), antibiotics (suchas dactinomycin (formerly actinomycin), bleomycin, daunorubicin(formerly daunomycin), doxorubicin, idarubicin, mithramycin, mitomycin,mitoxantrone, plicamycin, anthramycin (AMC)).

In one example, a CXCR4 binding molecule or polypeptide as describedherein is conjugated or linked to another protein (e.g. Human SerumAlbumin or HSA), including another CXCR4 binding molecule or polypeptideof the disclosure or a protein comprising a CDR1 and/or CDR3 region asdescribed herein. A CXCR4 binding molecule or polypeptide as describedherein may also be conjugated to another binding molecule or polypeptidewhich targets, for example, a tumour antigen, or a target that has thepotential to redirect and activate any circulating T cells againsttumors (for example CD3), or a target that is notably expressed onmonocytes and macrophages and upregulated upon activation on neutrophils(for example CD64) or a target that is expressed on the surface ofnatural killer cells, neutrophil polymorphonuclear leukocytes, monocytesand macrophages. In one example, the binding molecule or polypeptide isa low affinity binder of IgG (for example CD16) or a target that isconstitutively expressed primarily on neutrophils, monocytes,macrophages and eosinophils (for example CD89). Other proteins orconjugation partners are not excluded. Additional proteins will beapparent to the skilled artisan and include, for example, animmunomodulator or a half-life extending protein or a peptide orpolypeptide or other protein that binds to serum albumin amongst others.

Exemplary serum albumin binding peptides or protein are described inUS20060228364 or US20080260757.

In one example a CXCR4 binding molecule or polypeptide of the presentdisclosure is conjugated to an XTEN polypeptide as described inSchellenberger et al (2009) Nature Biotechnology 27(12):1186-1192.

In one example a CXCR4 binding molecule or polypeptide of the presentdisclosure is conjugated to a polypeptide as described in Schlapschy etal (2013) Protein Engineering, Design & Selection vol. 26 no. 8 pp.489-501.

In one example a polypeptide of the present disclosure is conjugated toan Fc region of an immunoglobulin as described, for example, in Peterset al (2010), Blood Vol. 115 no. 10 2057-2064, Kim et al, (2009) BMBRep. 42:212-216 and Nagashima et al (2011) J Biochem. 149: 337-346.

CXCR4 binding polypeptide conjugates (bispecific molecules) can beprepared using methods known in the art. For example, each bindingspecificity of the bispecific molecule can be generated separately andthen conjugated to one another. When the binding specificities areproteins, polypeptides or peptides, a variety of coupling orcross-linking agents can be used for covalent conjugation. Examples ofcross-linking agents include protein A, carbodiimide,N-succinimidyl-S-acetyl-thioacetate (SATA),5,5′-dithiobis(2-nitrobenzoic acid) (DTNB), o-phenylenedimaleimide(oPDM), N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), andsulfosuccinimidyl 4-(N-maleimidomethyl) cyclohaxane-1-carboxylate(sulfo-SMCC) (see e.g., Karpovsky el al. (1984) J. Exp. Med 160 1686,Liu, M A et al. (1985) Proc. Natl. Acad. Sci. USA 82 8648). Othermethods include those described in Paulus (1985) Behring Ins Mitt No 78,1 18-132, Brennan et al. (1985) Science 229 81-83 and Glennie et al.(1987). J Immunol 39 2367-2375).

A variety of radionuclides are available for the production ofradioconjugated proteins. Examples include, but are not limited to, lowenergy radioactive nuclei (e.g., suitable for diagnostic purposes), suchas 13C, 15N, 2H, 125I, 123I, 99Tc, 43K, 52Fe, 67Ga, 68Ga, 111In and thelike. For example, the radionuclide is a gamma, photon, orpositron-emitting radionuclide with a half-life suitable to permitactivity or detection after the elapsed time between administration andlocalization to the imaging site. The present disclosure alsoencompasses high energy radioactive nuclei (e.g., for therapeuticpurposes), such as 125I, 131I, 123I, 111In, 105Rh, 153Sm, 67Cu, 67Ga,166Ho, 177Lu, 186Re and 188Re. These isotopes typically produce highenergy α- or β-particles which have a short path length. Suchradionuclides kill cells to which they are in close proximity, forexample neoplastic cells to which the conjugate has attached or hasentered. They have little or no effect on non-localized cells and areessentially non-immunogenic. Alternatively, high-energy isotopes may begenerated by thermal irradiation of an otherwise stable isotope, forexample as in boron neutron-capture therapy (Guan et al., 1998). Otherisotopes which may be suitable are described in Carter. (2001) NatureReviews Cancer 1, 118-129, Goldmacher et al. (2011) Therapeutic Delivery2; 397-416, Payne (2003) Cancer Cell 3, 207-212, Schrama et al, (2006)Nature Rev. Drug Discov. 5, 147-159, Reichert et al. (2007) NatureReviews Drug Discovery 6; 349-356.

In another example, the protein is conjugated to a “receptor” (such asstreptavidin) for utilization in cell pretargeting wherein the conjugateis administered to the patient, followed by removal of unbound conjugatefrom the circulation using a clearing agent and then administration of a“ligand” (e.g., avidin) that is conjugated to a therapeutic agent (e.g.,a radionucleotide).

The CXCR4 binding molecules or polypeptides of the present disclosurecan be modified to contain additional nonproteinaceous moieties that areknown in the art and readily available. For example, the moietiessuitable for derivatization of the protein are physiologicallyacceptable polymer, e.g., a water soluble polymer. Such polymers areuseful for increasing stability and/or reducing clearance (e.g., by thekidney) and/or for reducing immunogenicity of a CXCR4 bindingpolypeptide of the disclosure. Non-limiting examples of water solublepolymers include, but are not limited to, polyethylene glycol (PEG),polyvinyl alcohol (PVA), or propropylene glycol (PPG).

In one example, a CXCR4 binding molecule or polypeptide as describedherein comprises one or more detectable markers to facilitate detectionand/or isolation. For example, the compound comprises a fluorescentlabel such as, for example, fluorescein (FITC), 5,6-carboxymethylfluorescein, Texas red, nitrobenz-2-oxa-I,3-diazol-4-yl (NBD), coumarin,dansyl chloride, rhodamine, 4′-6-diamidino-2-phenylinodole (DAPI), andthe cyanine dyes Cy3, Cy3.5, Cy5, Cy5.5 and Cy7, fluorescein(5-carboxyfluorescein-N-hydroxysuccinimide ester), rhodamine(5,6-tetramethyl rhodamine). The absorption and emission maxima,respectively, for these fluors are: FITC (490 nm; 520 nm), Cy3 (554 nm;568 nm), Cy3.5 (581 nm; 588 nm), Cy5 (652 nm: 672 nm), Cy5.5 (682 nm;703 nm) and Cy7 (755 nm; 778 nm).

In certain examples, the i-bodies of the present disclosure can becoupled with an agent useful in imaging tumors. Such agents include:metals; metal chelators; lanthanides; lanthanide chelators; radiometals;radiometal chelators; positron-emitting nuclei; microbubbles (forultrasound); liposomes; molecules microencapsulated in liposomes ornanosphere; monocrystalline iron oxide nanocompounds; magnetic resonanceimaging contrast agents; light absorbing, reflecting and/or scatteringagents; colloidal particles; fluorophores, such as near-infraredfluorophores. In many examples, such secondary functionality/moiety willbe relatively large, e.g., at least 25 amu in size, and in manyinstances can be at least 50,100 or 250 amu in size. In certainexamples, the secondary functionality is a chelate moiety for chelatinga metal, e.g., a chelator for a radiometal or paramagnetic ion. Inadditional examples, it is a chelator for a radionuclide useful forradiotherapy or imaging procedures.

Alternatively, or in addition, the CXCR4 binding molecule or polypeptideas described herein is labelled with, for example, a fluorescentsemiconductor nanocrystal (as described, for example, in U.S. Pat. No.6,306,610).

Alternatively, or in addition, the CXCR4 binding molecule or polypeptideis labelled with, for example, a magnetic or paramagnetic compound, suchas, iron, steel, nickel, cobalt, rare earth materials,neodymium-iron-boron, ferrous-chromium-cobalt, nickel-ferrous,cobalt-platinum, or strontium ferrite.

Immobilized Proteins

In one example a CXCR4 binding molecule or polypeptide of the disclosureis immobilized on a solid or semi-solid matrix. The term“immobilization” is to be understood to involve various methods andtechniques to fix proteins onto specific matrices, e.g. as described inWO99/56126 or WO02/26292. For example, immobilization can serve tostabilize the proteins so that its activity is not reduced or adverselymodified by biological, chemical or physical exposure, especially duringstorage or in single-batch use.

Various methods for immobilizing a protein on a matrix are known in theart and include crosslinking, binding to a carrier, and retention withina semi-permeable matrix.

Exemplary matrices include porous gels, aluminium oxide, bentonite,agarose, starch, nylon or polyacrylamide.

Assaying Activity of a CXCR4 Binding Molecule or Polypeptide of theDisclosure Binding Assays

The most specific and potent antibodies against G-protein coupledreceptors typically target conformationally-complex epitopes formed bythe tertiary structure of the proteins. The approaches used with regardto soluble protein targets are not effective for membrane spanningproteins, whose native structure depends on an intact lipid bilayer.

CXCR4 binding molecules or polypeptides of the present disclosure can betested for binding to CXCR4 by, for example, standard flow cytometricmethods. Since the CXCR4 binding molecules or polypeptides of thepresent disclosure preferably recognise human CXCR4 in its nativeconformation, binding to CXCR4 is preferably determined using an assaythat utilises a reagent expressing the native conformation of CXCR4.Non-limiting examples of reagents expressing native conformation CXCR4that can be used in the binding assays include cells that naturallyexpress CXCR4, cells that have been transfected to express CXCR4 (e.g.R1610 cells transfected with a CXCR4 expression vector). Examples ofsuitable cells that express CXCR4 include MDA-MB-231, MDA-MB-468,MDA-MB-361, MDA-MB-549, Ramos, Namalwa, MOLT-4, DU-4475, DU-145, PC3,LNcaP, SW480, HT29, NCI-H69, SJSA-1-met-luc and HL-60 cells. Briefly,for the flow cytometry assay, cells expressing CXCR4 are incubated withthe test CXCR4 binding molecule or polypeptide, washed, incubated with alabelled secondary reagent capable of binding to the test antibody,washed again, and subjected to analysis to detect the binding of thesecondary reagent to the cells (e.g. using a FACS machine). CXCR4molecules or polypeptides which stain cells brightly as evaluated byflow cytometry are used for further investigation. Examples of bindingassays suitable for use according to the present disclosure includeradioligand binding assays such as the filtration assay (PerkinElmer) orthe SPA assay (PerkinElmer or GE Healthcare), or tagged ligand bindingassays such as DELFIA™ TRF (PerkinElmer), LanthaScreen™ system(Invitrogen), or Tag-Lite™ system (Cisbio).

Alternatively a cell line such as a CHO cell line may be transfectedwith an expression vector encoding a transmembrane form of CXCR4. Thetransfected protein may comprise a tag, such as a myc-tag, preferably atthe N-terminus, for detection using an antibody to the tag. Binding of aCXCR4 binding molecule or polypeptide of this disclosure to CXCR4 may bedetermined by incubating the transfected cells with the CXCR4 bindingpolypeptide, and detecting bound polypeptide. Binding of an antibody tothe tag on the transfected protein may be used as a positive control.

A further approach for assessing binding requires the use oflipoparticles which are capable of incorporating high concentrations oftarget membrane proteins in their native conformations (e.g. magneticproteoliposomes incorporating CXCR4 or liposome particles incorporatingCXCR4). Such lipoprotein particles are described in, for example WO2005/042695, WO 2011/083141, Banik et al (2009) Drug Discovery &Development 12(9):14-17; Willis S et al (2008) Biochemistry 47:6988-90.Lipoparticles are produced from mammalian cells by co-expressing theretroviral structural core polyprotein, Gag, along with a desiredmembrane protein (e.g. CXCR4). Gag core proteins self assemble at theplasma membrane where they bud off and capture target membrane proteins.Lipoproteins are approximately 150 nm in diameter so are readilysuspended in aqueous solutions that can be used for inoculation. Becausemembrane proteins within lipoparticles are derived directly from thecell surface without mechanical disruption or detergents, the nativestructure and orientation of the membrane proteins is retained.Lipoproteins do not contain cytoplasmic proteins or inverted membraneproteins that can result in an unfocussed immune response. Thelipoproteins can be immobilised onto a solid support using standardtechniques and binding by the CXCR4 molecules or polypeptides accordingto the present disclosure analysed by surface Plasmon resonance (see forexample Maynard J A et al (2009) Biotechnol J 4(11):1542-1558, StenlundP et al (2003) Anal Biochem 316(2):243-50, Hoffman et al (2000) ProcNatl Acad Sci 97:11215-11220, WO 2005/042695).

Furthermore the lipoparticles can be mutated residue by residue todetermine which residues of CXCR4 the CXCR4 binding polypeptides of thepresent disclosure are binding. This validates critical residues thatrepresent amino acids whose side chains make the highest energeticcontributions to the interaction between the binding CXCR4 bindingpolypeptide and the CXCR4 epitope (Bogan and Thorn, (1998) J. Mol. Biol.280, 1-9; Lo Conte et al., (1999) J. Mol. Biol. 285, 2177-2198. Thecritical residues identified for i-body AM3-114, i-body AM4-272, andi-body AM3-523 binding were visualized on a CXCR4 dimer structure(derived from PDB ID #3ODU; Wu et al., (2010) Science 330: 1066-1071.

Another assay is an antigen binding assay, e.g., as described in ScopesIn: Protein purification: principles and practice, Third Edition,Springer Verlag, 1994. Such a method generally involves labelling theCXCR4 binding molecule or polypeptide and contacting it with immobilizedtarget or a fragment thereof, e.g., human CXCR4 or CXCR4 positivelipoparticle. Following washing to remove non-specific bound protein,the amount of label and, as a consequence, bound protein is detected. Ofcourse, the CXCR4 binding molecule or polypeptide can be immobilized andthe target labeled. Panning-type assays can also be used.

An exemplary method for determining an inhibitor of CXCR4 activity is acompetitive binding assay. For example, labelled SDF-1 is added to cellsexpressing CXCR4 or immobilised CXCR4 positive lipoparticles either witha CXCR4 binding molecule or polypeptide or after addition of the CXCR4binding molecule or polypeptide. Following washing to remove unboundSDF-1 and/or CXCR4 binding molecule or polypeptide, the amount of labelbound to CXCR4 is detected. This is compared to the amount boundfollowing incubation in the absence of CXCR4 binding molecule orpolypeptide, and a CXCR4 binding molecule or polypeptide that reducedthe amount of SDF-1 binding (i.e. bound label) is considered a CXCR4inhibitory agent.

Binding assays can also be used to detect receptor-mediated G-proteinactivation (e.g. Regulation of G Protein-Coupled Receptor Function andExpression ed. Benovic J L pp 119-132 (2000) Wiley-Liss NY). Such assaysinclude receptor-stimulated GTP binding to Ga subunits. Activation ofGPCR results in GDP-GTP exchange in the Ga subunit and this exchange canbe quantified and used as a direct measurement of the receptor-G proteininteraction. This typically involves the use of radiolabelled guaninenucleotide with the receptor in cell free membrane preparations orartificial lipid membranes. The amount of radiolabel incorporated isused as a measure of the extent of G protein activation.

Methods for assaying antigen-binding affinity are well known in the artand also include half-maximal binding assays, competition assays, andScatchard analysis.

Affinity Assays

Optionally, the dissociation rate constant (Kd), association rateconstant (Ka) or binding constant/equilibrium dissociation constant(K_(D), i.e., Koff/Kon) of a CXCR4 binding polypeptide is determined.These constants for a CXCR4 binding polypeptide may be measured by aradiolabeled or fluorescently-labeled CXCR4 binding assay. This assayequilibrates the CXCR4 binding polypeptide with a concentration of CXCR4positive lipoparticles. Following washing to remove unbound CXCR4, theamount of CXCR4 binding polypeptide is determined. According to anotherexample the constants are measured by using surface plasmon resonanceassays, e.g., using BIAcore surface plasmon resonance (BIAcore, Inc.,Piscataway, N.J.) with immobilized CXCR4 positive lipoparticles (WO2005/042695).

The dissociation rate constant (Kd) is used to calculate the off rate(koff), a constant used to calculate how quickly a binding moleculedissociates from its target. A flatter slope seem in BIAcore SPRanalysis indicates a slower off rate and hence stronger binding. Asteeper downside means a faster off rate/weaker antibody binding.

The association rate constant (Ka) is the part of the reaction used tocalculate the on rate, a constant used to characterise how quickly thebinding molecule binds to its target.

The ratio of experimentall measured off and on rates (Koff/Kon) is usedto calculate the K_(D) value. Most binding molecules have K_(D) valuesin the low micromolar (10⁻⁶) to nanomolar (10⁻⁷ to 10⁻⁹) range. Highaffinity antibodies are generally considered to be in the low nanomolarrange (10⁻⁹) with very high affinity antibodies being in the picomolar(10⁻¹²) range.

Functional Assays

The binding of a ligand, such as an agonist or SDF-1 to CXCR4 can resultin signalling by this G protein coupled receptor, and the activity of Gproteins as well as stimulating other intracellular signallingmolecules. The inhibitory or stimulatory activity of a CXCR4 bindingmolecule or polypeptide of the present disclosure can be determined withor without a ligand in a suitable assay, as well as the assessment ofthe ability of the CXCR4 binding molecule or polypeptide to inhibit orstimulate the activity in the presence or absence of the ligand.

The activity of the CXCR4 receptor by the CXCR4 binding molecule orpolypeptide of the present disclosure can be measured in a number ofways, for example alteration of β-arrestin modulation, alteration inintracellular Ca²⁺ concentration, activation of phospholipase C,alteration in intracellular inositol triphosphate QP3 concentration,alteration in intracellular diacylglycerol (DAG) concentration, andalteration in intracellular adenosine cyclic 3′,5′-monophosphate (cAMP)concentration.

G protein activity, such as hydrolysis of GTP to GDP, or latersignalling event triggered by receptor binding, such as induction ofrapid and transient increase in the concentration of intracellular(cytosolic) free calcium can be assayed by methods known in the art orother suitable methods (e.g. Neote et al (1993) Cell 72:415-425; VanRiper et al (1993) J. Exp. Med 177:851-856).

cAMP Assays

Activation of GPCRs by the polypeptides of the invention can bemonitored by measuring the increase or decrease in intracellular cAMPwith fluorescent dyes. Methods of measuring intracellular cAMP are knownin the art. Assays measuring cellular levels of cAMP are dependent onthe activity of adenylate cyclase, which is regulated by GPCRs coupledto Gα_(s) or Gα_(i/o) protein. Adenylate cyclase requirespre-stimulation with forskolin. In addition, to counteract the naturaldegradation of cAMP to AMP by phosphodiesterase (PDE) enzymes, aninhibitor of PDE (e.g. IBMX) might be required in the system duringassay optimisation. Examples of useful membrane permeant dyes includeacetoxymethyl ester forms of dyes that can be cleaved by intracellularesterases to form a free acid, which is no longer membrane permeant andremains trapped inside a cell. Assays designed to directly measurelevels of cAMP produced upon modulation of adenylate cyclase activity byGPCRs can also be used. Such assays are based on competition betweenendogenous cAMP and exogenously added biotinylated cAMP. Capture of cAMPis achieved by using a specific antibody conjugated to a solid materialsuch as a capture bead.

Radiometric assays such as the SPA cAMP assay (GE Healthcare) and theFlashPlate™ cAMP assay from PerkinElmer using ¹²⁵I-labelled cAMP arewidely used. More recently these assays have been replaced withluminescence or fluorescence based homogenous assays to avoid the use ofradioactivity. A further assay is the Enzyme Fragment Complementationassay (HitHunter™) by DiscovRx. Cellular cAMP competes with cAMPlabelled with a small peptide fragment of β-galactosidase for binding toan anti-cAMP antibody. The resulting free labelled cAMP complements withthe enzyme fragment, producing active β-galactosidase which is detectedwith fluorescent or luminescent substrates. AlphaScreen™ (PerkinElmer)is a sensitive bead-based proximity chemiluminescent assay. CellularcAMP competes with a biotinylated cAMP probe recognized by astreptavidin donor and anti-cAMP antibody-conjugated acceptor beads.Release of the biotinylated cAMP from the antibody results in thedissociation of the streptavidin donor from its acceptor, which can bemeasured as a decrease in the chemiluminescent signal.

In addition, fluorescence polarization (FP)-based cAMP kits areavailable from Perkin-Elmer, Molecular Devices and GE Healthcare.Furthermore, HTRF-based cAMP detection is available from Cisbio. Withthis method, novel donor (cAMP antibody labelled with europium cryptate)and acceptor (cAMP labelled with a modified allophycocyanin dye) pairsare designed to increase the stability of the signal and make this assayhighly sensitive and reproducible for cAMP measurement.

More recent commercial assays, such as the cAMP-Glo™ assay (Promega) areavailable for modulation of GPCRs that are coupled to Gα proteins whichin turn modulate adenylate cyclase. The assay is based on cAMP as apotent activator of the tetrameric, inactive cAMP-dependent proteinkinase (PKA) resulting in dissociation of its cAMP-bound regulatorysubunits and release of the free, active catalytic subunits. Activationof PKA can be monitored by measuring APT use in a kinase reaction with aluciferase/luciferin-based reaction. The amount of ATP consumed reflectsthe activation of PKA by cAMP.

β-Arrestin Recruitment Assay

Beta-arrestins are intracellular proteins that are recruited to the cellsurface following activation of the GPCR. They regulate the activity ofG protein-coupled receptors (GPCRs) (Luttrell et al. (2002) Journal ofCell Science, 115:455-465). In this case by the polypeptides of theinvention, resulting in desensitization and targeting of the receptorfor internalization. In addition to its role in receptordesensitization, termination of G protein-coupled signalling, andinternalization, β-arrestin also acts as a scaffolding protein to linkactivated GPCR's to additional intracellular signalling pathways such asactivation of c-Src, ERK 1/2 and Akt in a G protein-independent manner.Several methods are available for measuring β-arrestin recruitmentincluding, the TransFluor® assay (Molecular Devices) in which β-arrestinis coupled to GFP and upon receptor activation, diffuse cytoplasmicdistribution of GFP changes to formation of GFP containing pits orvesicles that are visualized with high content imaging system.

Several non-imaging-based β-arrestin recruitment assays, such asBioluminescence Resonance Energy Transfer (BRET) as described in Xu Y etal (1999) Proc Natl Acad Sci 96:151-6, PathHunter™ technology(DiscoveRx) and the Tango™ assay (Invitrogen), are available. In theBRET assay, the receptor of interest is tagged at the C-terminus with afluorescent protein tag (such as eGFP2, GFP10 or YFP) and the β-arrestinis tagged with a Renilla luciferase (RLuc) or vice versa. Uponβ-arrestin recruitment, the two tags come into close proximity and thelight emitted from the RLuc reaction excites the GFP, which then emits adetectable signal at a higher wavelength. BRET is calculated as theratio of the two emissions (GFP/RLuc).

Invitrogen's Tango™ GPCR Assay System is a platform based on aprotease-activated reporter gene. β-arrestin is fused to a TEV protease,while GPCR is extended at its C-terminus with a protease cleavage sitefollowed by the transcription factor Gal-VP16. Upon GPCR activation,protease-tagged arrestin is recruited to the receptor and the Gal-VP16that is fused to the receptor is cleaved and enters the nucleus toregulate the transcription of a β-lactamase reporter gene. Theβ-lactamase catalyzes the cleavage of a modified substrate tagged withtwo fluorophores, and the change in FRET signal between these twofluorophores can be monitored.

The PathHunter™ assay (DiscoveRx) utilizes enzyme fragmentcomplementation of β-galactosidase and subsequent enzymatic activity tomeasure receptor-β-arrestin interactions. In this assay, β-arrestin isfused to an N-terminal deletion mutant of β-galactosidase that iscatalytically inactive, and GPCR is tagged at the C-terminus with asmall (4 kDa) fragment derived from the deleted N-terminal sequence ofβ-galactosidase (ProLink™). Upon GPCR-β-arrestin interaction, the twoparts of β-galactosidase are brought into proximity, which results inthe activation of the enzyme, cleavage of the substrate and generationof a chemiluminescent signal.

Calcium Assays

Activation of GPCRs by the polypeptides of the invention can bemonitored by measuring the increase or decrease in intracellular calciumwith fluorescent dyes. The Ca2+ assay is very popular in GPCR screeningowing to the availability of cell-permeable Ca2+-sensitive fluorescentdyes (such as Fluo-3 and Fluo-4) and automated realtime fluorescenceplate readers, such as FLIPR™ (Molecular Device). Molecular Device alsooffers fluorescent dye kits, which contain proprietary quenchingmolecules that allow cellular loading of dye without the need ofsubsequent cell washing to remove excess dye. The integrated pipettingcapabilities of the FLIPR™ allow ultra high-throughput screening in 384-or 1536-well format with the ability to detect agonists, antagonists,and modulators all in one assay. The use of fluorescent dyes can also bereplaced by the use of Ca²⁺-sensitive biosensors. Recombinant expressionof the jellyfish photoprotein aequorin, which provides an intenseluminescent signal in response to elevated intracellular Ca²⁺ in thepresence of a coelenterazine derivative, has also been developed forfunctional screens of GPCRs (Eglen R M et al (2008) Assay Drug DevTechnol 6:659-71).

Additional commercial assays include the Fluo-4/Fluor-8 calciummobilisation assay (Invitrogen), and the Tango™ GPCR assay (LifeTechnologies).

Chemotaxis Assays

Chemotaxis assays can also be used to assess the ability of a CXCR4binding polypeptide of the invention to block binding of a ligand toCXCR4 and/or inhibit function associated with binding of the ligand tothe receptor (Fernandis et al. (2004) Oncogene 23: 157-167). Theseassays are based on the functional migration of cells in vitro or invivo induced by a compound (chemoattractant). Chemotaxis can be assessedby any suitable means, for example, in an assay utilising a 96-wellchemotaxis plate, or other art recognised method for assessingchemotaxis. In one example, Jurkat cells, MDA-MB-231, MDA-MB-468, PC3,or NCI-H69 cells can be assessed for migration utilising a chemotaxisassay. For example, Jurkat cells (5×10⁵ cells in 200 ml RPMI-1640) arepre-incubated with and without the polypeptides of the invention andSDF-1 and are added to the top well of a 6.5 mm diameter, 5-mM-porepolycarbonate Transwell culture insert (Costar, Cambridge, Mass.) with0.25% BSA. SDF-1 (fixed concentration), is added in the lower wells andcells incubated for migration at 37° C. for 4 h. Migrated cells in thelower chamber are counted with a ZM Coulter counter (CoulterDiagnostics, Hialeah, Fla.).

Proliferation Assays

The CXCR4 binding polypeptides of the present disclosure can be assessedfor their ability to inhibit cell proliferation of tumor cells (e.g.tumor cells expressing surface CXCR4 such as MDA-MB-231, MDA-MB-361,MDA-MB-549, Ramos, Namalwa, MOLT-4, DU-4475, DU-145, PC3, LNcaP, SW480,HT29, NCI-H69 and HL60), or in a cell line which has been engineered toexpress CXCR4. The CXCR4 binding polypeptides of the present disclosurecan also be assessed for their ability to inhibit cell proliferation ofCD34⁺ progenitor cells (e.g. Kahn et al. Overexpression of CXCR4 onhuman CD34+ progenitors increases their proliferation, migration, andNOD/SCID repopulation ((2004) Blood. 103:2942-2949). Cell proliferationassays will be known to persons skilled in the art. Examples of cellproliferation assays include the MTT Cell Proliferation Assay (ATCC),the CellTiter Aqueous Cell proliferation assay (Promega), alamarBlueAssay (Invitrogen), CyQUANT Direct Cell Proliferation assay (LifeTechnologies), for described in, for example WO01/081614, and U.S. Pat.No. 5,972,639.

Apoptosis Assays

The CXCR4 binding molecules or polypeptides of the present disclosurecan be assessed for their ability to induce apoptosis. Apoptosis assaysare available in a variety of formats which will be known to personsskilled in the art. These include:

(i) caspase assays e.g. PhiPhiLux® (Oncolmmunin, Inc), caspase 3activity assay (Roche Applied Science), caspase-Glo™ Assays (Promega),CaspACE™ Assay System (Promega), EnzChek® Caspase-3 assay kit(Invitrogen), Active Caspase-3 detection kits (Stratagene),Caspase-mediated apoptosis products (BioVision), CasPASE™ ApoptosisAssay Kit (Genentech);(ii) Tunnel and DNA Fragmentation Assays e.g. Apoptotic DNA Ladder Kit(Roche Applied Science), Cellular DNA fragmentation ELISA (Roche AppliedScience), DeadEnd™ TUNEL System (Promega), APO-BrdU™ TUNEL Assay Kit(Invitrogen), TUNEL Apoptosis Detection kit (Upstate), ApoptosisMebstain Kit (Bechman Coulter), Nuclear-mediated apoptosis kits(BioVision), apoptotic DNA Ladder Kit (Genentech);(iii) Cell Permeability Assays e.g. APOPercentage™ Assay (BiocolorAssays);(iv) Annexin V assays e.g. Annexin V, Alexa Fluor® (Invitrogen),Rhodamine 110, bis-(L-aspartic acid amide), trifluoroacetic acid salt(Invitrogen), Annexin V Apoptosis kits (BioVision);(v) Protein cleavage assays e.g. anti-poly (ADP-ribose) polymerase(Roche Applied Science), M30 CytoDEATH (Roche Applied Science);(vi) Mitochondrial and ATP/ADP assays e.g. ApoGlow® Rapid ApoptosisScreening kit, mitochondrial membrane potential detection kit(Stratagene) and Mitochondrial-mediated apoptosis products (BioVision);and(vii) a combination of annexin V and propidium iodide as described inthe examples disclosed herein.

Angiogenesis Assays

Angiogenesis is characterised by a number of cellular events includingendothelial cell migration, invasion and differentiation intocapillaries. In vitro endothelial tube formation assays are used as amodel for studying endothelial differentiation and modulation ofendothelial tube formation by antiangiogenic agents (see for exampleSharon McGonigle and Victor Shifrin Current Protocols in PharmacologyDOI: 10.1002/0471141755.ph1212s43 or Liang et al, (2007) Biochem BiophysRes Commun. August 3; 359(3): 716-722.). Typically endothelial tubeformation assays are performed using human umbilical vein endothelialcells (HUVEC), HMVEC and HMEC-1 cells. The cells are plated onto a layerof Matrigel at a density of 1×10⁵ cells/ml of M199 medium with 1% FBSand 200 ng/ml of CXCL12. After 18 hrs, the wells were photographed at 4×magnification and the number of their tubular networks is counted.

Receptor Dimerisation Assay

CXCR4 interacts with CXCR7, CCR5, β₂AR (β₂ adrenergic receptor), CCR2,DOR (Delta opiod receptor) and CCR7 at the plasma membrane to form aheterodimer, oligomer or even higher order complexes includinghomodimers with CXCR4. Compounds that specifically target GPRCheterodimers or affect receptor dimerisation may have potential toachieve specific therapeutic effects (Rozenfeld R et al (2011) Biochem J433:11-8). Various technologies have been established to monitorreceptor dimerization, including resonance energy transfer approaches(FRET or BRET).

In commonly used FRET or BRET-based approaches, donor and acceptormolecules are genetically fused to the C-terminus of GPCRs, which areoverexpressed in the cells. Resonance energy transfer occurs when donorand acceptor molecules are brought into close proximity as a consequenceof GPCR dimerization (reviewed in Achour L et al (2011) Methods Mol Biol756:183-200). However, one limitation of such traditional FRET and BRETassays is that in the overexpression system, resonance energy transfercan also occur within the intracellular compartments such that it isdifficult to demonstrate a specific signal resulting only from a directinteraction of proteins at the cell surface.

The GPCR dimerization assay as described in U.S. Pat. No. 8,283,127entitled ‘Detection System and Uses Therefor’ covers Dimerix's HeteromerIdentification Technology (HIT) assay configuration for ligand dependentidentification, monitoring and screening of heteromers of any twoproteins. It also covers the application of Dimerix's assay on allproximity based reporter systems.

The GPCR dimerization assay with Tag-Lite™ is a method combining TR-FRETwith SNAP-Tag™ technology (Cisbio), enabling quantitative analysis ofprotein-protein interactions at the surface of living cells in a 96- or384-well format. In this assay, GPCRs are tagged with either a SNAP- orCLIP-tag at the N-terminus, which can be subsequently labelled withtheir corresponding cell-impermeable substrates carrying appropriateTR-FRET-compatible fluorophores, typically using terbium cryptate as adonor and a green or red fluorescent molecule as an acceptor. Severalpossible dimer combinations exist in this assay: ¼ of the dimers containboth receptors labeled with the donor, ¼ of the dimers contain bothreceptors labeled with the acceptors, and ½ of the dimers contain onereceptor labeled with the donor and one receptor labelled with theacceptor. Only the last fraction will emit the FRET signal.

The PathHunter™ system (DiscoveRx) is another platform that can be usedfor GPCR heterodimerization analysis. Cell lines utilized in thepreviously described PathHunter™ β-arrestin recruitment assay can beused as the starting material. In these cell lines, β-arrestin is fusedto the larger portion of the β-galactosidase enzyme acceptor, and thesmaller 42-amino acid ProLink™ tag is attached to one of the GPCRtargets. A second untagged GPCR can be introduced into the cells and thetransactivation effects of the untagged GPCR on the ProLink™-tagged GPCRcan be measured by the recruitment of β-arrestin to the tagged-GPCRusing PathHunter detection reagents. The transactivation strength can beestimated as a ratio between the cellular response to the agonist of theuntagged GPCR and the response to the agonist of Prolink™-GPCR. Theassay can be used to investigate the interaction between GPCR pairs, aswell as screen for compounds that modulate GPCP activity throughenhancing or disrupting GPCR heterodimerization in a 384-well format,for example CXCR4 and CXCR7, CXCR4 and CCR5 or CXCR4 and β₂AR or CXCR4and DOR or CXCR4 and CCR2 or CXCR4 and CCR7.

Competitive Assays

Competition studies can be used to determine the ability of the CXCR4binding molecules including the ligand SDF-1 or polypeptides (i-bodies)to compete for binding to CXCR4. Typically, the CXCR4 i-bodies aretitrated in a 1:3 serial dilution series resulting in a concentrationrange, for example from 100 nm to 5 pM in the presence of a constantconcentration of SDF-1 or FITC-labelled human anti-CXCR4 antibody (e.g.12G5). The mixture is then added to CXCR4 expressing cells and allowedto bind. The ability of each i-body to compete with 12G5 for binding toCXCR4 expressing cells can be assessed by fluorescent cytometry anddetection of FITC.

Competition studies may also be performed utilising CXCR4 containinglipoproteins (IntegraMolecular) as described in WO 2005/042695.

The ability of the i-bodies of the present disclosure to bind to avariety of different cell lines can also be examined by flow cytometryby carrying out a FACS titration. Increasing amounts of the i-body canbe incubated with 100,000 cells and binding assessed by flow cytometry.The Bmax value can also be determined, which indicated approximately howmany CXCR4 molecules are present on each cell. Based on the bindingcurves, an EC50 for i-body binding can be determined. Examples ofsuitable cell lines include Ramos, Raji, Namalwa, L540, DMS79,MDA-MB-231, MDA-MB-361, MDA-MB-549, MOLT-4, DU-4475, DU-145, PC3, LNcaP,SW480, HT29, NCI-H69 and HL60.

The ability of the i-bodies of the present disclosure to bind todifferent subsets of human peripheral blood mononuclear cells (PBMCs)can also be examined. Human PBMCs can be isolated by standard methodsand the cellular subsets further isolated by FACS. Examples of cellularsubsets include one or more of the following CD3+, CD20+, CD11b+, andCD14+. Binding can be assessed by flow cytometry compared to a suitablecontrol as shown in the examples herein.

The competition assay may be performed using Iodine-125-labeled SDF-Iand a cell line, which naturally express CXCR4 or CXCR4 lipoparticles. Acomparison of the i-bodies on blocking SDF-I binding to the CXCR4expressing cell line can be performed by a standard radiolabeled ligandbinding assay. The i-bodies can be serially diluted 1:3 to yield a rangeof concentrations and then added to CXCR4 expressing cells in thepresence of ¹²⁵I-SDF-I with a specific activity of 2000 Ci/mmole(Amersham, catalog #EM314-25UCI). The total possible bound radiolabeledligand can be determined by allowing the ¹²⁵I-SDF-I to bind to CXCR4expressing cells in the absence of i-bodies for 2 hours at 40° C.Non-specific binding of the radio-labeled ligand can be determined byallowing the ¹²⁵I-SDF-I to bind in the presence of 1 μM unlabeled SDF-I(Peprotech, catalog #300-28A). The amount of cell-associated ¹²⁵I-SDF-Iis then determined by standard methods.

Alternatively unlabelled SDF-1 could be used to compete the binding ofthe i-body to lipoparticles overexpressing CXCR4. Binding of the i-bodyto these lipoparticles could be detected using an antibody to the Histag or to the FLAG tag. Increasing concentrations of SDF-1 will be addedand the amount of i-body remaining bound will be measured. This can bedone in an ELISA format where the CXCR4 lipoparticles are immobilised onplastic. This information will determine if the binding site of thei-body on CXCR4 is the same or near or different to the ligand SDF-1.

Protein Detection Assays

One example of the disclosure detects the presence of CXCR4 or a cellexpressing same or a lipoparticle containing CXCR4 within the membrane.The amount, level or presence of a protein or cell is determined usingany of a variety of techniques known to the skilled artisan such as, forexample, a technique selected from the group consisting of flowcytometry, immunohistochemistry, immunofluorescence, an immunoblot, aWestern blot, a dot blot, an enzyme linked immunosorbent assay (ELISA),radioimmunoassay (RIA), enzyme immunoassay, fluorescence resonanceenergy transfer (FRET), matrix-assisted laser desorption/ionization timeof flight (MALDI-TOF), electrospray ionization (ESI), mass spectrometry(including tandem mass spectrometry, e.g. LC MS/MS), biosensortechnology, evanescent fiber-optics technology or protein chiptechnology.

In one example the assay used to determine the amount or level of aprotein is a semi-quantitative assay.

In another example the assay used to determine the amount or level of aprotein is a quantitative assay.

For example, the protein is detected with an immunoassay, e.g., using anassay selected from the group consisting of, immunohistochemistry,immunofluorescence, enzyme linked immunosorbent assay (ELISA),fluorescence linked immunosorbent assay (FLISA), Western blotting,radioimmunoassay (RIA), a biosensor assay, a protein chip assay and animmunostaining assay (e.g. immunofluorescence).

Standard solid-phase ELISA or FLISA formats are particularly useful indetermining the concentration of a protein from a variety of samples.

In one form, an ELISA or FLISA comprises of immobilizing a CXCR4lipoparticle on a solid matrix, such as, for example, a membrane, apolystyrene or polycarbonate microwell, a polystyrene or polycarbonatedipstick or a glass support. A sample that includes the CXCR4 bindingmolecule or polypeptide of the disclosure is then brought into physicalrelation with the immobilised CXCR4 protein and then bound or‘captured’. The bound CXCR4 binding molecule or polypeptide is thendetected using a second labelled compound that binds to a tag sequencesituated on the end of the CXCR4 binding molecule or polypeptide.

It will be apparent to the skilled person that the assay formatsdescribed herein are amenable to high throughput formats, such as, forexample automation of screening processes or a microarray format.Furthermore, variations of the above-described assay will be apparent tothose skilled in the art, such as, for example, a competitive ELISA.

In an alternative example, a polypeptide is detected within or on acell, using methods known in the art, such as, for example,immunohistochemistry or immunofluorescence. Methods usingimmunofluorescence are exemplary, as they are quantitative or at leastsemi-quantitative. Methods of quantitating the degree of fluorescence ofa stained cell are known in the art.

Lipoparticles containing CXCR4 can be used to assess the binding of aCXCR4 binding molecule or polypeptide of the present disclosure withCXCR4. The CXCR4 protein embedded in the lipoparticle can be used inassays where soluble proteins or whole cells cannot be used, such asassays where the protein of interest (e.g. CXCR4) must be bound to asupport or substrate, for example an assay using a microfluidic devicee.g. a biosensor assay. In some examples a lipoprotein is attached to asurface and is then contacted with the CXCR4 binding molecule orpolypeptide of the disclosure and the biosensor detects the binding ofthe CXCR4 polypeptide of the invention to the lipoparticle. Thedetection can be by surface plasmon resonance, colorimetric diffractiongrating, deflection of micro cantilevers (Weeks B L et al (2003)Scanning 25(6):297-9), or acoustic wave response (Coper M A et al (2001)Nature Biotechnology 19, 833-837). In some examples the CXCR4 bindingmolecule or polypeptide is attached to a surface that is part of asensor and this is then contacted with a lipoparticle and the binding isdetected. The detection can be by surface plasmon resonance,colorimetric diffraction grating, deflection of microcantilevers, oracoustic wave response. In some examples, the CXCR4 binding molecule orpolypeptide and lipoparticle are contacted in solution.

Biosensor devices are designed to measure the interaction betweenbiological molecules. Biosensor devices generally employ an electrodesurface in combination with current or impedance measuring elements tobe integrated into a device in combination with the assay substrate(such as that described in U.S. Pat. No. 5,567,301). Typically,biosensors measure direct interactions between a protein of interest andpotential ligands that may bind to it. Biosensors are typically highlysensitive and can work with and detect even very weak or very smallquantity interactions. Biosensor devices have been constructed thatconsist of optical chips, fiber optics, spectrometer detectors,microchannel chips, nanowells and microcantilevers, and acoustic wavedevices. Some forms of biosensors known in the art also rely on surfaceplasmon resonance to detect protein interactions, whereby a change inthe surface plasmon resonance surface of reflection is indicative of aprotein binding to a ligand or antibody (U.S. Pat. No. 5,485,277 andU.S. Pat. No. 5,492,840).

In one example, the lipoparticle is attached to a sensor surface, wherea “sensor surface” is any substrate where a change in a property of thesubstrate mediated by the contacting the surface with a molecule orpolypeptide is detected and can be compared to the surface in theabsence of such contacting. However, in other examples, the lipoparticleis already attached to a sensor surface. While the sensor surface can bea biosensor chip, the sensor surface also includes any biosensor chipknown in the art e.g. Biacore C1 chip, a F1 chip, a glass substratecomprising a coating of e.g. gold.

Biosensors are of particular use in high throughput analysis due to theease of adapting such systems to micro- or nano-scales. Furthermore,such systems are conveniently adapted to incorporate several detectionreagents, allowing for multiplexing of diagnostic reagents in a singlebiosensor unit. This permits the simultaneous detection of severalproteins or peptides in a small amount of body fluids.

The present disclosure also encompasses any assay where the protein ofinterest is a membrane component (e.g. CXCR4) and where study of thebinding of the protein with a binding molecule or polypeptide requires,or is facilitated by presenting the protein in the context of a lipidbilayer and/or attaching the protein to a support or solid substrate.Such assays include assays using a microfluidic device, an opticalbiosensor, PATIR-FTIR spectroscopy, which is a type of biosensor usingtotal internal reflection Fourier-transform intrared spectroscopy(19998, Chem. Phys. Lipids 96:69-80), CPRW Biosensor (CoupledPlasmon-wavelength resonance (CPWR) spectroscopy as described in Salamonet al (1997) Biophys J 73:2791-2197), multipole coupling spectroscopy(MCS) as described in Signature biosceinces, fiber optic biosensors(Illumina) as described in Walt et al (200) Science 287:451-52 andDickinson et al (1996) Nature 382:697-700, lab-on-a-chip microfluidicsas described in Sundberg et al Current Opin in Biotech 11:47-53,microchannels (Gyros' microchannels etched into a compact disc-baseddevice, Microcantilevers as described in Tamayo et al (2001)Ultramicroscopy 86:167-173, confocal microscopy and nanowell detectionas described WO 01/02551 and microwell binding assays. In one example,the sensor surface comprises a 96-well, 384-well, 1536-well a nano-well,optical fiber or slide format.

Imaging Methods

As will be apparent to the skilled artisan from the foregoing, thepresent disclosure also contemplates imaging methods using a CXCR4binding molecule or polypeptide of the disclosure. For imaging, a CXCR4binding molecule or polypeptide is generally conjugated to a detectablelabel, which can be any molecule or agent that can emit a signal that isdetectable by imaging. However, a secondary labelled compound thatspecifically binds to a CXCR4 binding molecule or polypeptide of thedisclosure may also be used. Exemplary detectable labels include aprotein, a radioisotope, a fluorophore, a visible light emittingfluorophore, infrared light emitting fluorophore, a metal, aferromagnetic substance, an electromagnetic emitting substance asubstance with a specific magnetic resonance (MR) spectroscopicsignature, an X-ray absorbing or reflecting substance, or a soundaltering substance.

The CXCR4 binding molecule or polypeptide of the disclosure (and, ifused the labelled secondary compound) can be administered eithersystemically or locally to an organ, or tissue (or tumor, in the case ofa cancer) to be imaged, prior to the imaging procedure. Generally, theCXCR4 binding molecule or polypeptide is administered in doses effectiveto achieve the desired optical image of a tumor, tissue, or organ. Suchdoses may vary widely, depending upon the particular CXCR4 bindingmolecule or polypeptide employed, condition to be imaged, tissue, ororgan subjected to the imaging procedure, the imaging equipment beingused, and the like.

In some examples of the disclosure, the CXCR4 binding molecule orpolypeptide is used as in vivo optical imaging agents of tissues andorgans in various biomedical applications including, but not limited to,imaging of tumors, tomographic imaging of organs, monitoring of organfunctions, coronary angiography, fluorescence endoscopy, laser guidedsurgery, photoacoustic and sonofluorescence methods, and the like.

Examples of imaging methods include magnetic resonance imaging (MRI), MRspectroscopy, radiography, computerized tomography (CT), ultrasound,planar gamma camera imaging, single-photon emission computed tomography(SPECT), positron emission tomography (PET), other nuclearmedicine-based imaging, optical imaging using visible light, opticalimaging using luciferase, optical imaging using a fluorophore, otheroptical imaging, imaging using near infrared light, or imaging usinginfrared light.

In some examples, an imaging agent is tested using an in vitro or invivo assay prior to use in humans, e.g., using a model described herein.

Samples

To the extent that a method of the present disclosure is performed invitro, on an isolated tissue sample, rather than as an in vivo basedscreen, reference to “sample” should be understood as a reference to anysample of biological material derived from a subject such as, but notlimited to, a body fluid (e.g., blood or synovial fluid or cerebrospinalfluid), cellular material (e.g. tissue aspirate), tissue biopsyspecimens or surgical specimens.

The sample which is used according to a method of the present disclosuremay be used directly or may require some form of treatment prior to use.For example, a biopsy or surgical sample may require homogenization orother form of cellular dispersion prior to use. Furthermore, to theextent that the biological sample is not in liquid form, (if such formis required or desirable) it may require the addition of a reagent, suchas a buffer, to mobilize the sample.

As will be apparent from the preceding description, such an assay mayrequire the use of a suitable control, e.g. a normal or healthyindividual or a typical population, e.g., for quantification.

A “healthy subject” is one that has not been diagnosed as suffering froma condition, e.g., a CXCR4-related disease or disorder and/or is not atrisk of developing the disease or disorder.

Alternatively, or in addition, a suitable control sample is a controldata set comprising measurements of the marker being assayed for atypical population of subjects known not to suffer from a condition.

In one example, a reference sample is not included in an assay. Instead,a suitable reference sample is derived from an established data setpreviously generated from a typical population. Data derived fromprocessing, analyzing and/or assaying a test sample is then compared todata obtained for the sample population.

Pharmaceutical Compositions

CXCR4 binding molecules or polypeptides of the disclosure (syn. activeingredients) are useful for formulations into a pharmaceuticalcomposition for parenteral, topical, oral, or local administration,aerosol administration, or transdermal administration, for prophylacticor for therapeutic treatment. The pharmaceutical compositions can beadministered in a variety of unit dosage forms depending upon the methodof administration. For example, unit dosage forms suitable for oraladministration include powder, tablets, pills, capsules and lozenges.

The pharmaceutical compositions of the present disclosure are useful forparenteral administration, such as intravenous administration orsubcutaneous administration or administration into a body cavity orlumen of an organ or joint. The compositions for administration willcommonly comprise a solution of the CXCR4 binding molecule orpolypeptide of the disclosure dissolved in a pharmaceutically acceptablecarrier, such as an aqueous carrier. A variety of aqueous carriers canbe used, e.g., buffered saline and the like. The compositions maycontain pharmaceutically acceptable carriers as required to approximatephysiological conditions such as pH adjusting and buffering agents,toxicity adjusting agents and the like, for example, sodium acetate,sodium chloride, potassium chloride, calcium chloride, sodium lactateand the like. The concentration of binding molecules or polypeptides ofthe present disclosure in these formulations can vary widely, and willbe selected primarily based on fluid volumes, viscosities, body weightand the like in accordance with the particular mode of administrationselected and the patients needs. Exemplary carriers include water,saline, Ringer's solution, dextrose solution, and 5% human serumalbumin. Nonaqueous vehicles such as mixed oils and ethyl oleate mayalso be used. Liposomes may also be used as carriers. The vehicles maycontain minor amounts of additives that enhance isotonicity and chemicalstability, e.g., buffers and preservatives.

A CXCR4 binding molecule or polypeptide of the disclosure can beformulated for parenteral administration, e.g., formulated for injectionvia the intravenous, intramuscular, subcutaneous, transdermal, or othersuch routes, including peristaltic administration and directinstillation into a tumor or disease site (intracavity administration).The preparation of an aqueous composition that contains the compounds ofthe present disclosure as an active ingredient will be known to those ofskill in the art.

Suitable pharmaceutical compositions in accordance with the disclosurewill generally include an amount of the CXCR4 binding molecule orpolypeptide of the present disclosure mixed with an acceptablepharmaceutical carrier, such as a sterile aqueous solution, to give arange of final concentrations, depending on the intended use. Thetechniques of preparation are generally known in the art as exemplifiedby Remington's Pharmaceutical Sciences, 16th Ed. Mack PublishingCompany, 1980.

Upon formulation, compounds of the present disclosure will beadministered in a manner compatible with the dosage formulation and insuch an amount as is therapeutically/prophylactically effective.Suitable dosages of compounds of the present disclosure will varydepending on the specific compound, the condition to be treated and/orthe subject being treated. It is within the ability of a skilledphysician to determine a suitable dosage, e.g., by commencing with asub-optimal dosage and incrementally modifying the dosage to determinean optimal or useful dosage.

Exemplary dosages and timings of administration will be apparent to theskilled artisan based on the disclosure herein.

Compositions of the present disclosure can be combined with othertherapeutic moieties or imaging/diagnostic moieties. For example, apharmaceutical composition of the present disclosure may comprise anadditional active agent selected from the group consisting ofbisphosphonates, active vitamin D3, calcitonin and derivatives thereof,hormone preparations such as estradiol, SERMs (selective estrogenreceptor modulators), ipriflavone, vitamin K2 (menatetrenone), calciumpreparations, PTH (parathyroid hormone) preparations, nonsteroidalanti-inflammatory agents, soluble TNF receptor preparations,anti-TNF-[alpha] binding molecules, antibodies or functional fragmentsof the antibodies, anti-PTHrP (parathyroid hormone-related protein)binding molecules, antibodies or functional fragments of the antibodies,IL-1 receptor antagonists, anti-IL-6 receptor binding molecules,antibodies or functional fragments of the antibodies, anti-VEGF-Abinding molecules or antibodies anti-CD20 binding molecules orantibodies, anti-PDL-1 or anti-PD1 binding molecules or antibodies,anti-CCL2 binding molecules or antibodies, anti-CCR2 binding moleculesor antibodies, anti-RANK-L binding molecules, or functional fragments ofthe antibodies or i-bodies.

A pharmaceutical composition of the present disclosure also may includea pharmaceutically acceptable anti-oxidant. Examples of pharmaceuticallyacceptable antioxidants include (1) water soluble antioxidants, such asascorbic acid, cysteine hydrochloride, sodium bisulfate, sodiummetabisulfite, sodium sulfite and the like, (2) oil-solubleantioxidants, such as ascorbyl palmitate, butylated hydroxyanisole(BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate,alpha-tocopherol, and the like, and (3) metal chelating agents, such ascitric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaricacid, phosphoric acid, and the like.

Pharmaceutical compositions of the present disclosure also can beadministered in combination therapy, i.e., combined with other agents.For example, the combination therapy can include a CXCR4 bindingmolecule or polypeptide of the present disclosure combined with at leastone other anti-cancer, anti-inflammatory or immunosuppressant agent.

Examples of anti-cancer or chemotherapeutic agents may includeMitoxantrone, etoposide, Azacitidine, Lenalidomide, Temozolomide,Decitabine, Ganetespib, Clofarabine Cytarabine, Daunorubicin,vinorelbine, azacitidine, sorafenib, rituximab, bevacizumab orbortezomib.

These compositions may also contain adjuvants such as preservatives,wetting agents, emulsifying agents and dispersing agents. Prevention ofpresence of microorganisms may be ensured both by sterilizationprocedures, and by the inclusion of various antibacterial and antifungalagents, for example, paraben, chlorobutanol, phenol sorbic acid, and thelike. It may also be desirable to include isotonic agents, such assugars, sodium chloride, and the like into the compositions. Inaddition, prolonged absorption of the injectable pharmaceutical form maybe brought about by the inclusion of agents which delay absorption suchas aluminum monostearate and gelatine.

The amount of active ingredient which can be combined with apharmaceutically acceptable carrier to produce a single dosage form willvary depending upon the subject being treated, and the particular modeof administration. The amount of active ingredient which can be combinedwith a carrier material to produce a single dosage form will generallybe that amount of the composition which produces a therapeutic effect.Generally, out of one hundred percent, this amount will range from about0.01 percent to about ninety-nine percent of active ingredient (i.e.CXCR4 binding polypeptide), in one example from about 0.1 percent toabout 70 percent, in one example from about 1 percent to about 30percent of active ingredient in combination with a pharmaceuticallyacceptable carrier. Dosage regimens are adjusted to provide the optimumdesired response (e.g., a therapeutic response). For example, a singlebolus may be administered, several divided doses may be administeredover time or the dose may be proportionally reduced or increased asindicated by the exigencies of the therapeutic situation. It isespecially advantageous to formulate parenteral compositions in dosageunit form for ease of administration and uniformity of dosage. “Dosageunit form” as used herein refers to physically discrete units suited asunitary dosages for the subjects to be treated. Each unit contains apredetermined quantity of active compound calculated to produce thedesired therapeutic effect in association with the requiredpharmaceutical carrier. The specification for the dosage unit forms ofthis disclosure are dictated by and directly dependent on (a) the uniquecharacteristics of the active compound and the particular therapeuticeffect to be achieved, and (b) the limitations inherent in the art ofcompounding such an active compound for the treatment of sensitivity inindividuals. For administration of the CXCR4 binding molecule orpolypeptide, the dosage ranges from about 0.0001 to 100 mg/kg, and moreusually 0.01 to 5 mg/kg, of the host body weight. For example, dosagescan be 0.3 mg/kg body weight, 1 mg/kg body weight, 3 mg/kg body weight,5 mg/kg body weight or 10 mg/kg body weight or within the range of 1-10mg/kg. An exemplary treatment regime entails administration once perday, once per week, once every two weeks, once every three weeks, onceevery four weeks, once a month, once every 3 months or once every threeto 6 months. Preferred dosage regimens for a CXCR4 binding molecules orpolypeptides of this disclosure include 1 mg/kg body weight or 3 mg/kgbody weight via intravenous administration, with the antibody beinggiven using one of the following dosing schedules (i) every four weeksfor six dosages, then every three months, (ii) every three weeks, (iii)3 mg/kg body weight once followed by 1 mg/kg body weight every threeweeks.

Actual dosage levels of the active ingredients in the pharmaceuticalcompositions of the present disclosure may be varied so as to obtain anamount of the active ingredient which is effective to achieve thedesired therapeutic response for a particular patient, composition, andmode of administration, without being toxic to the subject. The selecteddosage level will depend upon a variety of pharmacokinetic factorsincluding the activity of the particular compositions of the presentdisclosure employed, or the ester, salt or amide thereof, the route ofadministration, the time of administration, the rate of excretion of theparticular compound being employed, the duration of the treatment, otherdrugs, compounds and/or materials used in combination with theparticular compositions employed, the age, sex, weight, condition,general health and prior medical history of the patient being treated,and like factors well known in the medical arts. A “therapeuticallyeffective dosage” of a CXCR4 binding molecule or polypeptide of thisdisclosure preferably results in a decrease in severity of diseasesymptoms, an increase in frequency and duration of disease symptom-freeperiods, or a prevention of impairment or disability due to the diseaseaffliction. For example, for the treatment of CXCR4⁺ tumors, a“therapeutically effective dosage” preferably inhibits cell growth ortumor growth by at least about 20%, at least about 40%, at least about60%, or at least about 80% relative to untreated subjects. The abilityof a compound to inhibit tumor growth can be evaluated in an animalmodel system predictive of efficacy in human tumors. Alternatively, thisproperty of a composition can be evaluated by examining the ability ofthe compound to inhibit cell growth, such inhibition can be measured invitro by assays known to the skilled practitioner. A therapeuticallyeffective amount of a therapeutic compound can decrease tumor size, orotherwise ameliorate symptoms in a subject. One of ordinary skill in theart would be able to determine such amounts based on such factors as thesubjects size, the severity of the subject's symptoms, and theparticular composition or route of administration selected.

Therapeutic compositions can be administered with medical devices knownin the art. For example, a therapeutic composition of the presentdisclosure can be administered with a needleless hypodermic injectiondevice, such as the devices disclosed in U.S. Pat. Nos. 5,399,163,5,383,851, 5,312,335, 5,064,413, 4,941,880, 4,790,824, or 4,596,556.Examples of well-known implants and modules useful in the presentdisclosure include U.S. Pat. No. 4,487,603, which discloses animplantable micro-infusion pump for dispensing medication at acontrolled rate, U.S. Pat. No. 4,486,194, which discloses a therapeuticdevice for administering medicants through the skin, U.S. Pat. No.4,447,233, which discloses a medication infusion pump for deliveringmedication at a precise infusion rate, U.S. Pat. No. 4,447,224, whichdiscloses a variable flow implantable infusion apparatus for continuousdrug delivery, U.S. Pat. No. 4,439,196, which discloses an osmotic drugdelivery system having multi-chamber compartments, and U.S. Pat. No.4,475,196, which discloses an osmotic drug delivery system. Many othersuch implants, delivery systems, and modules are known to those skilledin the art.

In one example, the compositions are formulated to be free of pyrogenssuch that they are capable for administration to human patients.

The present disclosure also contemplates the use of any of the CXCR4binding polypeptide/i-body compositions of the present disclosure tomake a medicament for treating a disorder of the present disclosure.Medicaments can be packaged in a suitable pharmaceutical package withappropriate labels for the distribution to hospitals and clinicsaccording to indication on the label.

Uses of CXCR4 Binding Polypeptides

The CXCR4 binding molecules or polypeptides of the present disclosurehave numerous in vitro and in vivo diagnostic and therapeutic utilitiesinvolving the diagnosis and treatment of CXCR4 related diseases anddisorders. For example, these molecules can be administered to cells inculture, in vitro or ex vivo, or to human subjects, e.g., in vivo, totreat, prevent and to diagnose a variety of disorders. Preferredsubjects include human subjects having disorders mediated by ormodulated by CXCR4 activity or involving the CXCR4/SDF-1 pathway. When aCXCR4 binding polypeptide is administered together with another agent,the two can be administered in either order or simultaneously. Given thespecific binding of the CXCR4 binding molecules or polypeptides of thisdisclosure for CXCR4, they can be used to specifically detect CXCR4expression on the surface of cells and, moreover, can be used to purifyCXCR4 positive cells via immunoaffinity purification.

Target-specific effector cells, e g, effector cells linked tocompositions of this disclosure can also be used as therapeutic agents.Effector cells for targeting can be human leukocytes such asmacrophages, neutrophils or monocytes. Other cells include eosinophils,natural killer cells and other IgG- or IgA-receptor bearing cells. Ifdesired, effector cells can be obtained from the subject to be treated.The target-specific effector cells can be administered as a suspensionof cells in a physiologically acceptable solution. The number of cellsadministered will vary depending on the therapeutic purpose. In general,the amount will be sufficient to obtain localization at the target cell,e.g, a tumor cell expressing CXCR4, and to effect cell killing by, e g.phagocytosis.

Therapy with target-specific effector cells can be performed inconjunction with other techniques for removal of targeted cells. Forexample, anti-tumor therapy using the compositions of the presentdisclosure and/or effector cells armed with these compositions can beused in conjunction with chemotherapy. Additionally, combinationimmunotherapy may be used to direct two distinct cytotoxic effectorpopulations toward tumor cell rejection. For example, CXCR4 bindingpolypeptides linked to anti-Fc-gamma receptor or anti-CD3 may be used inconjunction with IgG- or IgA-receptor specific binding agents.Bispecific and multispecific molecules of the present disclosure canalso be used to modulate FcγR or FcγR levels on effector cells, such asby capping and elimination of receptors on the cell surface.

As a co-receptor for HIV entry into T cells, CXCR4 is known to beinvolved in HIV infection. Additionally, the CXCR4/SDF-1 pathway hasbeen shown to be involved in inflammatory conditions. Still further, theCXCR4/SDF-1 pathway has been shown to be involved in angiogenesis orneovascularisation. Accordingly, the CXCR4 binding polypeptides of thepresent disclosure can be used to modulate CXCR4 activity in a number ofclinical situations, as detailed below.

The present disclosure also provides methods for diagnosing or detectinga CXCR4 related disease or disorder as described herein. Any suitablemethod for detection and analysis of CXCR4 can be employed. As usedherein, the term “sample” refers to a sample from a human, animal, or toa research sample, e.g., a cell, tissue, organ, fluid, gas, aerosol,slurry, colloid, or coagulated material. Samples also include, but arenot limited to, protein or membrane extracts of cells, biological fluidssuch as sputum, blood, serum, plasma, or urine, or biological samplessuch as formalin-fixed or frozen tissue sections employing antibodiesdescribed herein. The term “sample” can also refer to a cell, tissue,organ, or fluid that is freshly taken from a human or animal, or to acell, tissue, organ, or fluid that is processed or stored. The samplecan be tested in vivo, e.g., without removal from the human or animal,or it can be tested in vitro. The sample can be tested after processing,e.g., by histological methods.

Various diagnostic assay techniques known in the art can be used, suchas competitive binding assays, direct or indirect sandwich assays andimmunoprecipitation assays conducted in either heterogeneous orhomogeneous phases (Zola, Monoclonal Antibodies: A Manual of Techniques,CRC Press, Inc. (1987) pp. 147-158). The antibodies used in thediagnostic assays can be labeled with a detectable moiety. Thedetectable moiety directly or indirectly produces a detectable signal.For example, the detectable moiety can be any of those described hereinsuch as, for example, a radioisotope, such as 3H, 14C, 32P, 35S, or125I, a fluorescent or chemiluminescent compound, such as fluoresceinisothiocyanate (FITC), Texas red, cyanin, photocyan, rhodamine, orluciferin, or an enzyme, such as alkaline phosphatase, /3-galactosidaseor horseradish peroxidase. Any method known in the art for conjugatingthe antibody to the detectable moiety can be employed, including thosemethods described by Hunter et al., Nature, 144:945 (1962); David etal., Biochemistry, 13:1014 (1974); Pain et al., J. Immunol. Meth.,40:219 (1981); and Nygren, J. Histochem. and Cytochem., 30:407 (1982).

Provided herein is a method of diagnosing a condition associated withCXCR4 comprising assessing a level of CXCR4 and/or SDF-1 in a sample ofa subject, wherein a change in level of CXCR4 and/or SDF-1 in the samplein comparison with a reference sample indicates the presence or increaseof a tumor or metastasis or fibrosis. In one aspect, the conditionassociated with CXCR4 or SDF-1 is a tumor, a metastasis, angiogenesis,or fibrosis. An increase in CXCR4 and/or SDF-1 levels in the sample incomparison with a reference sample can indicate the presence of a tumoror metastasis or an increase in tumor or metastatic growth or fibrosis.The reference sample can be a sample taken from the subject at anearlier time point or a sample from another individual. The level ofCXCR4 and/or SDF-1 levels in the sample can be detected by contactingthe sample with the CXCR4 binding molecule, polypeptide or i-bodythereof described herein. In one embodiment, the CXCR4 binding molecule,polypeptide or i-body thereof is detectably labeled.

In another example, a method is provided for diagnosing cancermetastasis in a subject having a tumor, comprising: assessing CXCR4levels or activity in the tumor, whereby a change in CXCR4 levels oractivity in the tumor in comparison with a reference sample indicatesthe presence of metastatic tumor growth. In some instances, the CXCR4levels or activities in the tumor can be higher than those when measuredearlier, which can indicate that the subject is at a greater risk ofcancer metastasis; that the cancer has metastasized; or that cancermetastasis has increased. The reference sample can derive from the samesubject, taken from the same tumor at a different time point or fromother site of the body, or from another individual.

In another example, a method is provided for diagnosing the leval orrate of progression of fibrosis in a subject having fibrosis,comprising: assessing CXCR4 levels or activity in the tissue, blood,plasma or biological fluids, whereby a change in CXCR4 levels incomparison with a reference sample indicates the presence of fibrosis.In some instances, the CXCR4 levels or activities can be higher thanthose when measured earlier, which can indicate that the subject is at afaster progressor of disease. The reference sample can derive from thesame subject, taken from the same tissue, blood, plasma or biologicalfluids at a different time point or from other site of the body, or fromanother individual.

Methods of Treatment

Methods are provided herein for treating or preventing a CXCR4 relateddisease or disorder. The methods comprise administering atherapeutically effective amount of a CXCR4 binding molecule orpolypeptide and another therapeutic agent.

CXCR4 has been shown to be expressed by a variety of cancer types and incertain situations an inverse correlation has been established betweenCXCR4 expression and subject prognosis or survival. Non-limitingexamples of cancer types associated with CXCR4 expression includebreast, prostate, non-small cell lung, pancreatic, thyroid,nasopharyngeal carcinoma, melanoma, renal cell carcinoma, lymphoma (e.g.non-Hodgkin's lymphoma), neuroblastoma, glioblastoma, rhabdomyosarcoma,colorectal, kidney, osteosarcoma, acute lymphoblastic leukemia, andacute myeloid leukemia.

Thus, in one example according to the present disclosure, a CXCR4binding molecule or polypeptide of the present disclosure can be used totreat a CXCR4 related disease or disorder, wherein the disease iscancer, and wherein the cancer includes, but is not limited to a cancerselected from the group consisting of bladder cancer, breast cancer,colorectal cancer, endometrial cancer, head & neck cancer, leukemia,lung cancer, lymphoma, melanoma, non-small-cell lung cancer, ovariancancer, prostate cancer, testicular cancer, uterine cancer, cervicalcancer, thyroid cancer, gastric cancer, brain stem glioma, cerebellarastrocytoma, cerebral astrocytoma, ependymoma, Ewing's sarcoma family oftumors, germ cell tumor, extracranial cancer, Hodgkin's disease,leukemia, acute lymphoblastic leukemia, acute myeloid leukemia, livercancer, medulloblastoma, neuroblastoma, brain tumors generally,non-Hodgkin's lymphoma, osteosarcoma, malignant fibrous histiocytoma ofbone, retinoblastoma, rhabdomyosarcoma, soft tissue sarcomas generally,supratentorial primitive neuroectodermal and pineal tumors, visualpathway and hypothalamic glioma, Wilms' tumor, acute lymphocyticleukemia, adult acute myeloid leukemia, adult non-Hodgkin's lymphoma,chronic lymphocytic leukemia, chronic myeloid leukemia, esophagealcancer, hairy cell leukemia, kidney cancer, multiple myeloma, oralcancer, pancreatic cancer, primary central nervous system lymphoma, skincancer, Myelodysplastic Syndrome and small-cell lung cancer.

In one example according to the present disclosure, a CXCR4 bindingmolecule or polypeptide of the present disclosure can be used to inhibitmetastatic tumour cell growth.

In one example according to the present disclosure a CXCR4 bindingmolecule or polypeptide of the present disclosure can be used to treatfibrosis.

The CXCR4 binding molecule or polypeptide of the present disclosure canbe used alone or in combination other cancer treatments, such as surgeryand/or radiation, and/or with other anti-neoplastic agents, such as theanti-neoplastic agents discussed and set forth above, includingchemotherapeutic drugs and other anti-tumor antigen antibodies, such asthose that bind CD20, Her2, PD-1, PDL-1, IL-2, PSMA, Campath-1, EGFR andthe like.

The CXCR4 binding molecule or polypeptide of the present disclosure canbe used alone or in combination with other inflammatory and fibrosistreatments.

CXCR4 has been shown to be a coreceptor for HIV entry into T cells and,additionally, certain murine anti-CXCR4 antibodies have beendemonstrated to be able to inhibit entry of HIV isolates into T cells(see Hou, T et al. (1998) J Immunol 160 180-188, Carnec, X et al. (2005)J Virol 79 1930-1938). Thus, CXCR4 can be used as a receptor by virusesfor entry into the cell and antibodies or other blocking agents can beused to inhibit cell entry of such viruses that use CXCR4 as a receptor.Thus, in one example, the CXCR4 binding molecules or polypeptides ofpresent disclosure can be used to inhibit entry of a virus into a cell,wherein the virus uses CXCR4 as a receptor for cell entry, such thatviral infection is inhibited. In one example, the CXCR4 bindingmolecules or polypeptides are used to inhibit entry of HIV into T cells,e.g, in the treatment or prevention of HIV/AIDS. The CXCR4 bindingmolecule or polypeptide can be used alone or in combination with otheranti-viral agents, such as anti-retroviral drugs such as AZT or proteaseinhibitors.

CXCR4 has been found to form a heterodimer with CXCR7 and regulatedCXCL12-mediated G protein signalling (Levoye A et al (2009) Blood113(24):6085-6093). The CXCR4/CXCR7 heterodimer has also been shown torecruite beta-arrestin to enhance cell migration (Decaillot F M et al(2011) J Biol Chem 286(37):32188-97). Accordingly, the CXCR4 bindingmolecules or polypeptides of the present disclosure can be administeredalone or together with agents that target the CXCR7 receptor asdescribed in for example, WO 2007/115231, WO 2007/115232, WO2008/048519, WO 2008/109154, WO 2010/054006. CXCR4 has also been foundto form a heterodimer with CCR5 (Sohy et al J Biol Chem. 2009 284;31270-31279), β₂AR (La Rocca et al J Cardiovasc Pharmacol. 2010 56;548-559) CCR2 (Sohy et al J Biol Chem. 2007 282; 30062-30069), DOR(Delta opiod receptor) (Pello et al Eur. J. Immunol. 2008 38; 537-549)or CCR7. Accordingly, the CXCR4 binding molecules or polypeptides of thepresent disclosure can be administered alone or together with agentsthat target these receptors.

The CXCR4/SDF-1 pathway has been shown to play a role in a variety ofinflammatory conditions, including but not limited to inflammatory liverdisease (Terada, R et al. (2003) Lab. Invest 83:665-672), autoimmunejoint inflammation (Matthys, P et al. (2001) J. Immunol 167 4686-4692),allergic airway disease (Gonzalo, J A et al (2000) J. Immunol165-499-508), and periodontal disease (Hosokawa, Y et al (2005) Clin.Exp. Immunol 4:467-474).

Accordingly, CXCR4 binding molecules or polypeptides of the presentdisclosure that inhibit binding of SDF-I to CXCR4 can be used to inhibitinflammation, inflammatory disorders, including disorders selected fromthe group consisting of inflammatory liver disease, autoimmune jointinflammation, allergic airway disease, periodontal disease (induced byPorphyromonas gingivalis) (Hajishengallis et al PNAS 2008 105;13532-13537), rheumatoid arthritis, inflammatory bowel disease, systemiclupus erythematosus, Type I diabetes, inflammatory skin disorders (e.g.,psoriasis, lichen planus), skin repair and regeneration (burns,scarring), eye (AMD, uveitis) systemic sclerosis, radiation inducedfibrosis, autoimmune thyroid disease, Sjogren's syndrome, pulmonaryinflammation (e.g., chronic obstructive pulmonary disease, pulmonarysarcoidosis, lymphocytic alveolitis, idiopathic pulmonary fibrosis),multiple sclerosis (Kohler et al Brain Pathology 2008, 18; 504-516),sepsis (Ding et al Crit Care Med 2006 34; 3011-3017) and inflammatorykidney disease (e.g., IgA nephropathy, glomerulonephritis). The CXCR4binding polypeptide can be used alone or in combination with otheranti-inflammatory agents, such as non-steroidal antiinflammatory drugs(NSAIDs), corticosteroids (e.g., prednisone, hydrocortisone),methotrexate, COX-2 inhibitors, TNF antagonists (e.g., etanercept,infliximab, adalimumab) and immunosuppressants (such as6-mercaptopurine, azathioprine and cyclosporine A).

Accordingly, CXCR4 binding molecules or polypeptides of the presentdisclosure that inhibit binding of SDF-I to CXCR4 can be used to inhibitfibrosis, in fibrotic disorders, including disorders selected from thegroup consisting of lung fibrosis (Idiopathic pulmonary fibrosis, fungalcystic fibrosis (Carevic et al Eur Respir J 2015 46; 395-404), pulmonaryarterial hypertension (Farkas et al PLoSONE 2014 9; e89810), radiationinduced fibrosis (Shu et al PLoSONE 2013; 8; e79768.) and systemicsclerosis, asthma (Lukacs et al AJP 2012 160; 1353-1360 & Nagase et al JImmunol 2000; 164: 5935-5943)), liver fibrosis (nonalcoholicsteatohepatitis (NASH) (Boujedidi et al Clinical Science 2015 128;257-267)), kidney fibrosis (hypertension and chronic kidney disease(Yuan et al Am J Physiol Renal Physiol. 2014 308; 459-472)), eyefibrosis (proliferative vitroretinopathy, diabetic retinopathy (Butleret al The Journal of Clin Invest 2005 115; 86-93), retinopathy ofprematurity (Villalvilla et al Life Sciences 2012 91; 264-270),noninfectious uveitis (Zhang et al Experimental Eye Research 2009 89;522-531), and wet-AMD (U.S. Pat. No. 7,964,191)), cardiac fibrosis(hypertension, ischemic cardiomyopathy, endomyocardial fibrosis,arterial fibrosis (Chu et al Circ Heart Fail. 2011 4; 651-658)), skinfibrosis (hypertrophic scarring (Ding et al Wound Rep and Reg 2014 22;622-630), burn related scarring (Avniel et al Journal of InvestigativeDermatology 2006 126; 468-476), diabetic wounds, scleroderma or systemicsclerosis (Tourkina et al Fibrogenesis & Tissue Repair 2011, 4;10.1186/1755-1536-4-15)). The CXCR4 binding molecules or polypeptides ofthe current invention can be used alone or in combination with otheranti-fibrotic agents, for example Pirfenidone or Nintedanib.

It has been demonstrated that SDF-1 induces neovascularization throughrecruitment of CXCR4-expressing hemangiocytes (Jin, D. K. et al. (2006)Nat Med. 12:557-567). CXCR4 has also been found to be essential forvascularisation of the gastrointestinal tract (Tachibana et al. (1998)Nature 393(6685):591-4). Moreover, blockade of the SDF-1/CXCR4 pathwaycan attenuate in vivo tumor growth by inhibiting angiogenesis in aVEGF-independent manner (Guleng, B. et al. (2005) Cancer Res.65:5864-58-71). Accordingly, the CXCR4 binding molecules or polypeptidesof the present disclosure that inhibit binding of SDF-I to CXCR4 can beused to inhibit angiogenesis by interfering with the SDF-1/CXCR4pathway. Inhibition of angiogenesis can be used, for example, to inhibittumor growth or tumor metastasis (regardless of whether the tumor isCXCR4⁺). The CXCR4 binding molecule or polypeptide can be used alone orin combination with other anti-angiogenic agents, such as anti-VEGF(Grunewald M et al (2006) Cell 124(1):175-89) or PDGF-D antibodies orfragments of antibodies.

Lack of Mobilisation of Stem Cells by the i-Bodies of the PresentDisclosure-Potential Applications

Various cytokines, chemokines and adhesion molecules have beenimplicated in the regulation CD34⁺ stem cell mobilisation (reviewed inGazitt, Y. (2001). J Hematother. Stem Cell Res. 10:229-236), includingthe interaction of CXCR4 and SDF-I. Moreover, a small molecule CXCR4antagonist has been demonstrated to stimulate rapid mobilization ofCD34⁺ stem cells from the bone marrow to the periphery (see e.g, Devine,S M et al. (2004) J. Clin. Oncol 22 1095-1 102; Broxmeyer, H E et al.(2005) J. Exp. Med 201:1307-1318, Flomenberg, N et al (2005) Blood106:1867-1874).

In contrast, some of the i-bodies of the present disclosure were foundto lack stem cell mobilisation ability. There are several studies thatindicate that CXCR4 inhibitors/antagonists that do not mobilise stemcells, such as the i-bodies described herein, will be useful inlong-term studies and treatment of chronic diseases.

i) Fibrosis Treatment

The response to injury involves the activation of adaptive mechanismsdesigned not only to maintain homeostasis but also to induce tissuerepair. This potential for regenerative repair is evident in humans incertain circumstances such as following hepatic resection or acutetubular necrosis. However, in the presence of chronic or repeatedinjury, the response mostly involves a combination of disorderedparenchymal cell regeneration in conjunction with the production oflarge quantities of ECM, eventually leading to the formation of aconnective tissue scar. While this repair by connective tissue clearlyassists in the maintenance of organ integrity following, for instance, askin wound, its presence in the other organs such as the heart, kidneyand lungs is often detrimental (Wynn et al Nat Med (2012) 18:1028-1040).

There is an unmet clinical need for the treatment of fibrosis (Luppi etal Curr Respir Care Rep (2012) 1:216-223, Friedman et al Sci Transl Med.(2013) 5:16750). Importantly, there are no current therapeuticstrategies that target the pro-fibrotic inflammatory processes and henceindicate a clear unmet clinical need to develop new therapeutic agents.Accordingly, strategies that inhibit pro-inflammatory cytokineactivation and pathological accumulation of ECM provide a potentialtherapeutic target for prevention of pathological organ fibrosis.

(a) Lung Fibrosis: Idiopathic Pulmonary Fibrosis (IPF)

Idiopathic pulmonary fibrosis (IPF) is an interstitial inflammatorydisease characterized by scarring and fibrosis of the lungs ultimatelyresulting in terminal respiratory insufficiency. Recent studies presentevidence that circulating fibrocytes that express CXCR4 contribute tothe pathogenesis of pulmonary fibrosis (Phillips et al J Clin Invest(2004) 114: 438-446.). This and other recent studies suggest thatblocking the activity of the CXCR4 on these fibrocytes might be usefulapproach for therapy in patients with various types of fibrosis,including fibrosis associated with pulmonary disease, diabetes andcardiovascular disease.

b) Occular Fibrosis

The pathological growth of new blood vessels in the posterior eye is adevastating consequence of a number of diseases including Age relatedMacular Degeneration, proliferative diabetic retinopathy and Retinopathyof Prematurity. Advanced, vision threatening, Age Related MacularDegeneration (referred to as Wet AMD) affects 5.7% of all people over 85years. Diabetic retinopathy is the most feared complication of diabetesaffecting approximately 40% of those with Type II diabetes and 86% ofthose with type I diabetes (Cheung et al Lancet 2010; 376: 124-36).Another retinal vascular disease, called Retinopathy of Prematurity, isa devastating consequence of premature birth, and remains the leadingcause of childhood blindness in the Western world. A common feature ofthese conditions is the abnormal growth of blood vessels and subsequentscar formation that is the crucial event leading to blindness. In orderto prevent blindness from these diseases, treatments that target bothabnormal growth of retinal blood vessels as well as subsequent scarringare necessary

Wet AMD is currently treated with a monthly or bimonthly injection intothe eye of a humanized antibody or antibody fragment that blocks theaction of the angiogenic growth factor, Vascular Endothelial GrowthFactor (VEGF). These new treatments have transformed the clinical careof those with Wet AMD and prevents the sudden loss of vision in amajority of patients (Rosenfeld et al N Engl J Med 2006; 355: 1419-31;Brown et al N Engl J Med 2006; 355: 1432-44). The CXCR4 binding moleculeor polypeptides of the current invention can be used for the treatmentof scaring and fibrotic related disorders of the eye includingvitreoretinopathy, diabetic retinopathy and retinopathy of prematurity.

ii) Atherosclerosis Treatment

Zernecke and colleagues (Zernecke et al (2008) Circulation Research102:09-217) provide evidence that the CXCL12/CXCR4 axis is protective inatherosclerosis and this protective effect is due to the control ofmyeloid cell homeostasis. These studies show that long-term inhibitionof the CXCR4 by the small molecule antagonist AMD3465 aggravateddiet-induced atherosclerotic lesion development in two different mousestrains (Apoe^(−/−) mice and Ldlr^(−/−)). CXCR4 antagonism with AMD3465has been shown to be 10-fold more effective than AMD3100 at releasingneutrophils from the bone marrow (Hatse et al. Biochem Pharmacol. 2005;70:752-761). Zernecke et al also demonstrated that prolonged treatmentwith AMD3465 led to an expansion of myeloid neutrophils and a slightincrease in monocytes, which appeared to correlate with a reduction oflymphocytes in the bone marrow. They concluded that “caution seemswarranted when attempting therapy with CXCR4 antagonists, which canmobilize hematopoietic cells but may inhibit the recruitment ofplaque-stabilizing progenitor subsets and may thus promoteatherosclerosis”. Thus, agents that lack the ability to mobilisehematopoietic cells may be useful in the treatment of atherosclerosis.The CXCR4 binding molecule or polypeptides of the current invention havethe ability to have anti-atheroscerotic effects while not increasingstem cell mobilization.

iii) Kidney Disease

A study by Zuk et al (2014) Am J Physiol Renal Physiol October 1;307(7):F783-97, provides compelling evidence that CXCR4 inhibitionameliorates acute kidney injury by inhibiting leukocyte infiltration andexpression of pro-inflammatory cytokines rather than via any effect onhematopoetic stem cells or their mobilisation. Thus, the CXCR4 bindingmolecules or polypeptides of the present disclosure may be useful in thetreatment of kidney disease.

iv) Angiogenesis

SDF-1 and its receptor, CXCR4 have been implicated in angiogenesis andscar formation (fibrosis)(Ferrara et al Nature 2005; 438: 967-74).Indeed, SDF-1 is increased in the vitreous of those with wet AMD,proliferative diabetic retinopathy and retinopathy of prematurity(Scotti et al Retina 2014; 34: 1802-10, Butler et al J Clin Invest 2005;115: 86-93, Sonmez et al Ophthalmology 2008; 115: 1065-1070). Itsreceptor, CXCR4, is localized to the growing tips of pathologicallygrowing blood vessels. Moreover, inhibition of CXCR4 has been shown toprevent the abnormal growth of vessels in a rodent model of choroidalneovascularization and retinopathy of prematurity (Lima e Silva et alFASEB J 2007; 21: 3219-30). Another study has shown that circulatingfibrocytes may function as precursors of myofibroblasts in Proliferativevitreoretinopathy (PVR) membranes. In PVR epiretinal membranes, therewere high numbers of cells expressing CXCL12 and CXCR4 and suggestedthat the CXCL12/CXCR4 chemokine axis appears to be predominant for therecruitment of fibrocytes into the eye in patients with PVR (Abu El-Asaret al Br J Ophthalmol 2008; 92:699-704).

In order to improve the clinical management of these vascular diseases,a treatment is needed that targets both angiogenesis and subsequentfibrosis. The novel polypeptides or i-bodies of the present disclosureare useful for such treatment.

Thus, the CXCR4 binding molecules, polypeptides or i-bodies of thepresent disclosure could be effective in reducing angiogenesis andsubsequent scarring in models of vascular disease of the posterior eyein AMD, proliferative diabetic retinopathy, retinopathy of prematurity,proliferative vitreoretinopathy, uvetis, corneal angiogenesis.

Inflammatory Models

The ability of the CXCR4 binding molecules or polypeptides of thepresent disclosure to inhibit inflammation can be examined ininflammatory mouse models. These models include the murine experimentalcolitis model, the carrageenan-induced paw edema model and thebleomycin-induce lung fibrosis model as described in Liang Zhongxing etal (2012) PLoS ONE 7(4): e34038.doi:10.1371.

Fibrotic Models

The ability of the CXCR4 binding molecules or polypeptides of thepresent disclosure to inhibit fibrosis can be examined in the bleomycinrodent model. In the rodent bleomycin model, which is used frequently tomimic idiopathic pulmonary fibrosis (IPF), SDF-1 levels are increased inserum and bronchial alveolar lavage fluid. Moreover, neutralizingantibodies to CXCR4 and the small molecule CXCR4 antagonist, AMD3100,were found to reduce lung eosinophilia, indicating that CXCR4-mediatedsignals contribute to lung inflammation in a mouse model of allergicairway disease (Gonzalo et al J Immunol. 2000; 165:499-508, Lukacs et alAm J Pathol. 2002; 160:1353-60). These data strongly indicate that CXCR4has a prominent role in promoting fibrosis than re-epithelialisation.The CXCR4 binding molecule or polypeptides of the current invention canbe used as an anti-fibrotic agent.

To date, several CXCR4 antagonists have been developed (Tsutsumi et alBiopolymers. 2007; 88: 279-289). Blocking CXCR4 using an antagonist suchas TN14003, MSX-122 or AMD3100 has been shown to effectively alleviatebleomycin induced pulmonary fibrosis (Xu et al Cell Mol Biol. 2007; 37:291-299). AMD3100 (Plerixafor), an FDA-approved small molecule CXCR4antagonist, has also been tested on bleomycin treated mice. WhileAMD3100 is effective at blocking stem cell homing, it also increasesstem cell mobilization, which has led to its use for increasing stemcell yields in preparation for autotransplantation. TN14003, a 14-merpeptide, blocks development of pulmonary fibrosis in bleomycin-treatedmice, while MSX-122, a small molecule has also demonstrated superiorityover TN14003 and AMD3100 in completely preventing bleomycin-induced lungfibrosis (Xu et al Cell Mol Biol. 2007; 37: 291-299) and irradiated micethat received MSX-122 had significant reductions in development ofpulmonary fibrosis while AMD3100 did not significantly suppress thisfibrotic process (Shu et al PLoS ONE 2013; 8(11): e79768.). The CXCR4binding molecule or polypeptides of the current invention have theability to block stem cell homing while not increasing stem cellmobilization.

An alternative technique to elucidate the role of novel targets in thepathogenesis of IPF involves isolation of fibroblasts from patients withthe disease and comparing mediator release to fibroblasts from healthysubjects. In this process, cells are exposed to pharmacologic agonistsand antagonists. The fibroblasts can be embedded and cultured inthree-dimensional matrices and cocultured with other cell types. Theability of the CXCR4 binding molecules or polypeptides of the presentdisclosure to inhibit fibrosis can be examined with the human patientfibroblasts.

Yet another translational model is the implantation of fibroblasts frompatients with IPF into immunodeficient mice. The ability of the CXCR4binding molecules or polypeptides of the present disclosure to inhibitfibrosis can be examined in this animal model of fibrosis (Murray et al,American Journal of Respiratory Cell and Molecular Biology Volume 50Number 5, May 2014).

Cancer/Metastasis Models

The ability of the CXCR4 binding molecules or polypeptides of thepresent disclosure to inhibit metastasis can be examined in mousemodels. These models include the breast cancer model (via administrationof MDA-MB-231 cells), the head and neck cancer animal model (viaadministration of 686LN-Ms cells) and the uveal melanoma micrometastasismodel as described in Liang Zhongxing et al (2012) PLoS ONE 7(4):e34038.doi:10.1371.

In Vivo Angiogenesis Assay

The ability of the CXCR4 binding molecules to inhibit angiogenesis canbe examined in a mouse model. These models are described in Liang et al,(2007) Biochem Biophys Res Commun. August 3; 359(3): 716-722, wherebyMDA-MB-231 cells are implanted subcutaneously into the flanks of nudemice.

Kits

In some examples, the CXCR4 binding molecule or polypeptides may beprovided in a kit or pharmaceutical package.

In one example, the present disclosure relates to kits for carrying outthe administration of a CXCR4 binding molecule described herein.

Pharmaceutical packages and kits can additionally include an excipient,a carrier, a buffering agent, a preservative or a stabilizing agent in apharmaceutical formulation. Each component of the kit can be enclosedwithin an individual container and all of the various containers can bewithin a single package. Invention kits can be designed for roomtemperature or cold storage. Additionally, the preparations can containstabilisers to increase shelf life of the kits and include, for examplebovine serum albumin (BSA) or other known conventional stabilizers.Where the compositions are lyophilized, the kit can contain furtherpreparations of solutions to reconstitute the preparations. Acceptablesolutions are well known in the art and include, for example,pharmaceutically acceptable phosphate buffered saline (PBS).

Additionally, the pharmaceutical packages or kits provided herein canfurther include any of the other moieties provided herein such as, forexample, a chemotherapeutic agent as described elsewhere in more detail.

Pharmaceutical packages and kits of the present invention can furtherinclude the components for an assay provided herein, such as, forexample, an ELISA assay. Alternatively, preparations of the kits areused in immunoassays, such as immunohistochemistry to test patienttissue biopsy sections.

Pharmaceutical packages and kits of the present invention can furtherinclude a label specifying, for example, a product description, mode ofadministration and indication of treatment. Pharmaceutical packagesprovided herein can include any of the compositions as described herein.The pharmaceutical package can further include a label for preventing,reducing the risk of, or treating any of the disease indicationsdescribed herein.

Kits of the present disclosure can additionally include labels orinstructions for using the kit components in any method of theinvention. A kit can include an i-body compound of the presentdisclosure in a pack, or dispenser together with instructions foradministering the compound in a method of the disclosure. Instructionscan include instructions for practicing any of the methods of thedisclosure described herein including treatment, detection, monitoringor diagnostic methods. Instructions may additionally include indicationsof a satisfactory clinical endpoint or any adverse symptoms that mayoccur, or additional information required by regulatory agencies such asthe Food and Drug Administration for use on a human subject.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the above-describedembodiments, without departing from the broad general scope of thepresent disclosure. The present embodiments are, therefore, to beconsidered in all respects as illustrative and not restrictive. Thepresent disclosure includes the following non-limiting examples.

General Methods Biacore Assay

(FIG. 2, 5, 11, 17) Kinetic binding analysis of selected i-bodies withimmobilized CXCR4 lipoparticles were performed at 25° C. using BiacoreT200 instrument (GE Healthcare, Uppsala, Sweden). Streptavidinimmobilization was performed in 1×HBS-P+ running buffer (10 mM HEPES,150 mM NaCl, 0.05% [v/v] Tween-20). Amine coupling kit (GE Healthcare)and the instructions therein were utilized for the attachment ofStreptavidin (Sigma; diluted to 100 pg/mL in 10 mM sodium acetate bufferpH 4.5) in all four channels on the sensor chip surface simultaneously,resulting in >6,000 RU of Streptavidin being coupled (1 RU=1 pgprotein/mm²). All binding experiments involving lipoparticles wereperformed with 1×HBS/BSA (10 mM HEPES, 150 mM NaCl, 1 mg/mL BSA) asinstrument running buffer. Biotinylated CXCR4 lipoparticles (IntegralMolecular, Cat#LEV-101B; 3.6 U/mL as described in WO 2005/042695) weretypically diluted 1 in 20 in the running buffer and immobilized onto aStreptavidin containing channel by injecting at 2 μL/mL for 1,800 secresulting in captured response levels of greater than 2,500 RU.Biotinylated CCR5 and null lipoparticles, used as off-target controls,were immobilized in a similar manner. In order to determine bindingkinetics, serial dilutions (three-fold) of i-bodies diluted in 1×HBS/BSAwere injected over immobilized lipoparticles with the association anddissociation phases monitored for 60 sec and 600 sec, respectively. Acontrol measurement of the instrument running buffer (“zero-buffer”blank) solution was also included for double referencing purposes.Collected experimental data were processed using Scrubber software(www.biologic.com.au). Kinetic parameters (ka=association andkd=dissociation rate constants) and equilibrium dissociation constant(KD=kd/ka) were derived by fitting each set of experimental data to aLangmuir 1:1 binding model. All interaction measurements were performedin triplicate and the derived binding parameters reported as averagedvalues±standard deviation.

Beta-Arrestin (BRET) Assay

(FIGS. 3 and 14) BRET was used in this study to assess the real-timekinetic profiles resulting from any consequent increase in proximity,building upon the previously validated monitoring of GPCR/β-arrestininteractions utilizing BRET. BRET occurs between a complementary Renillaluciferase (Rluc) variant as donor and green fluorescent protein variantas acceptor. Upon Rluc-catalyzed oxidation of the coelenterazinesubstrate (such as coelenterazine h for first generation BRET (BRET) orEnduRen for extended BRET (eBRET), energy is transferred to the acceptorif within 10 nm, resulting in acceptor light emission peaking at acharacteristic wavelength. BRET β-arrestin assays were carried out asdescribed previously (See, H. B., Seeber, R. M., Kocan, M., Eidne, K. A.and Pfleger, K. D. (2011) ‘Application of G protein-coupledreceptor-heteromer identification technology to monitor beta-arrestinrecruitment to G protein-coupled receptor heteromers’, Assay Drug DevTechnol, 9(1), 21-30, 10.1089/adt.2010.0336). CXCR4/Rluc8 cDNAconstructs were generated from plasmids containing the respectivereceptor cDNA tagged with Rluc kindly provided by Aron Chakera (OxfordUniversity, United Kingdom). The β-arrestin 2/Venus cDNA construct wasprepared previously from pCS2-Venus kindly provided by Atsushi Miyawaki(RIKEN Brain Science Institute, Wako-city, Japan). BRET technology incells transiently expressing CXCR4/Rluc8 and β-arrestin2/Venus in thepresence of 100 nM SDF-1 agonist was evaluated in the presence of theCXCR4 agonist SDF-1/CXCL12 and the i-bodies. HEK293FT cells weremaintained at 37° C., 5% CO₂ in Complete Media (Dulbecco's modifiedEagle's medium containing 0.3 mg/mL glutamine, 100 IU/mL penicillin, and100 mg/mL streptomycin; Gibco) supplemented with 10% fetal calf serum(FCS) and 400 mg/mL Geneticin (Gibco). Transfections were carried out 24h after seeding using Genejuice (Novagen) according to manufacturer'sinstructions. Cells were harvested with 0.05% Trypsin-EDTA (Gibco).HEK293FT cells were transfected using FuGene6 (Promega). 5 μMcoelenterazine h (Promega) in HBSS was used as the luciferase substratesolution. Cells were harvested 24 h post-transfection in HEPES-bufferedphenol red-free Complete Medium containing 5% FCS and added to apoly-L-lysine-coated white 96-well plate (Nunc). Dose-response curveswere generated using BRET, with medium in the plate being replaced withPBS containing 5 mM coelenterazine h (Molecular Probes) and assayscarried out immediately. For these assays, 48 h post-transfection, theplate was incubated at 378C, 5% CO₂ for 2 h with 30 mM EnduRen (Promega)to ensure substrate equilibrium was reached. All BRET measurements weretaken at 37° C. using the VICTOR Light plate reader with Wallac 1420software (PerkinElmer). Filtered light emissions were sequentiallymeasured at 400-475 and 520-540 nm. The BRET signal was calculated bysubtracting the ratio of 520-540 nm emission over 400-475 nm emissionfor a vehicle-treated cell sample from the same ratio for a secondaliquot of the same cells treated with agonist (in this instance in thepresence of SDF-1 or CXCL12) and i-body (ADCX-99, ADCX-272, ACDX-6,ACDX-306, ADCX-668) at various concentrations. Data are mean±S.E.M. offour independent experiments carried out in duplicate.

(FIG. 9) The PathHunter® β-Arrestin assay (DiscoveRx) was performedaccording to the manufacturer's protocol. Cells were seeded into whitewalled, 384-well tissue culture-treated microplates (Corning) andnormalized at 5,000 cells (or 10,000 cells for CXCR4) in a total volumeof 20 μL. Cell growth was at 37° C. (5% CO₂, 95% relative humidity).I-bodies or AMD3100 (Tocris Bioscience) (5 μL at 0.5-3.8 μM) were addedto singlicate wells and the plates were incubated at 37° C. for 30 min.Agonists were then added at the EC80 concentration and incubation wascontinued at 37° C. for 90 min (or 180 min for CCR1). Assay signal wasgenerated through a single addition of 15 μL (50% v/v) of PathHunterDetection reagent cocktail, followed by 1 h incubation at roomtemperature. Microplates were read following signal generation with aPerkinElmer Envision instrument for chemiluminescent signal detection ofrelative light units (RLU). Compound activity was analyzed using theCBIS data analysis suite (ChemInnovation). % inhibition=100%×[1−(meanRLU of test sample−mean RLU of vehicle control)/(mean RLU of EC80control−mean RLU of vehicle control)].

Im7-FH corresponds to an N-terminal solubility and purification tagwherein Im7 is an E. coli protein (Hosse R J et al (2009) Anal Biochem15; 385(2):346-57 and FH is flag+6 Histidine residues.

Example 1—Identification of CXCR4 Blocking i-Bodies

The principles learnt from shark IgNAR antibody structures can besuccessfully applied to the generation of binding repertoires of humanI-set domains from the immunoglobulin superfamily, which is furtherdescribed in WO 2005/118629. Shark IgNAR antibodies are structurallyclose to the immunoglobulin superfamily of I-set domains such as Domain1 of NCAM. The modified Domain 1 of NCAM is referred to as the i-bodyscaffold. Using this scaffold, a library of polypeptides is created anddisplayed on phage for screening against particular targets for specificbinders to that target. Such libraries are anticipated to primarilycontain variability in the CDR1 and CDR3 analogous regions.

An i-body library was created which had a random amino acid sequence inthe CDR1 region (represented by XXXXXX in FIG. 1B) and in the CDR3region (represented by Y′n in FIG. 1B), wherein n (the number of aminoacids in the random CDR3 sequence) is varied randomly between 10 and 20amino acids in length and sequence as per SEQ ID NO:2. The i-bodies ofthe disclosure comprise a scaffold region which corresponds to aminoacid resdiues 1 to 26, 33 to 79 and 88 to 97 of SEQ ID NO:1 or asequence at least 60% identical thereto or otherwise may comprisebetween one and five amino acid additions or substitutions. In oneexample, the scaffold region comprises the sequence set forth in SEQ IDNO:2 or the sequence set forth in SEQ ID NO:2 comprising between 1 and 5amino acid additions or substitutions.

The complementarity determining regions (CDR1 and CDR3) of SEQ ID NO:2are modified by amino acid addition and/or substitution relative to thecorresponding CDR1 and/or CDR3 regions in SEQ ID NO:1 represented byamino acid positions 27 to 32 and 80 to 86 in SEQ ID NO:1 respectively.The resulting i-body polypeptides are able to bind to human CXCR4 withan affinity of less than 50 μM.

In one example A′ and B′ in SEQ ID NO:2 are any amino acid residue.

In one example, A′ in SEQ ID NO:2 is amino acid Q or K and B′ in SEQ IDNO:2 is amino acid residue V or A. In a further example, A′ is Q and B′is V or A in SEQ ID NO:2.

Sequence ID NO:2 may further comprise between 1 and 4 consecutiveN-terminal amino acid residues selected from the group consisting of M,EAEA, MA, or MP.

I-bodies displayed on phage were selected against human CXCR4 (hCXCR4)displayed in a lipoparticle or expressed in a HEK cell line, followingincubation of the i-body library and hCXCR4 lipoparticle captured onplates or beads or with CXCR4 positive cells in solution. Extensivewashing was completed to remove non-specific binders in either format.Enrichment to the hCXCR4 positive lipoparticles or cells was observedand single colonies were picked and grown. The sequence of the i-bodyscaffold remains the same except for the specific regions of the CDR1and CDR3 regions. The CDR1 and CDR3 sequences of the single coloniesthat specifically bound to hCXCR4 are detailed in Table 1. Theaffinities of the i-bodies to CXCR4 are described in Table 1 and FIG. 5for ADCX-99 and FIG. 2 for i-bodies ADCX-306, ADCX-272 and ADCX-668.

The ability of i-body binders ADCX-99, ADCX-272, ADCX-6, ADCX-306, andADCX-668 to modulate β-arrestin is also demonstrated in FIG. 3.

TABLE 1 Panel of i-bodies identified to hCXCR4 SEQ ID NO. K_(D) NameCDR1 Sequence CDR3 Sequence of i-body (μM) ADCX-99 SGSDIR YRTGGYRHRALVLG11  0.7 (SEQ ID NO: 12) (SEQ ID NO: 13) ADCX-272 HLEVRS EQRGRSQSYFS  14 1.6 (SEQ ID NO: 15) (SEQ ID NO: 16) ADCX-6 LTSLEG EDHPQYSKME 17 ND(SEQ ID NO: 18) (SEQ ID NO: 19) ADCX-54 RTIIVE VLSIRGKWEL  20 ND(SEQ ID NO: 21) (SEQ ID NO: 22) ADCX-LS IAEFST QVSDHPEAGILWRG 23 ND(SEQ ID NO: 24) (SEQ ID NO: 25) ADCX-668 TIWYEQ WTRPVTSSMH 26 42  (SEQ ID NO: 27) (SEQ ID NO: 28) ADCX-306 FQEWVN TMPHTLNNLDVRT 29 22  (SEQ ID NO: 30) (SEQ ID NO: 31) ND = not determined.

In addition, a control i-body was generated, designated 21H5 which doesnot bind to CXCR4. This was used as an isotype control. The sequence ofthis i-body is shown below:

(SEQ ID NO: 82) LQVDIVPSQGEISVGESKFFLCQVAGDAKDKDISWFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVTGSDAMSNYSYPISE SEATVNVKIFQ

Example 2—Characterisation of CXCR4 Blocking i-Bodies

2.1 I-Body Expression and Purification in E. coli

I-bodies were expressed and purified using an E. coli expression system.I-bodies were expressed with various affinity tags including E coli.immunity protein (Im7) FLAG and 6×HIS (designated Im7-FH in FIG. 4).I-bodies were purified from the periplasmic fraction and the cytoplasmusing the various tags using anti-FLAG resin or Ni-NTA resinrespectively. The results of size exclusion chromatography are shown inFIG. 4.

2.2 I-Body Expression and Purification in Pichia

Genes for the i-bodies were cloned into a Pichia expression vector.After some optimisation of clone selection, the protein titres rangedfrom 3-9 mg/L at the small (2 ml scale). At the fermentation scale theyields were between 26-150 mg/L. Further parameters such as(temperature, pH, feed rate and feed strategy) could be optimised at thefermentation level to improve yields. After large-scale expression andpurification the i-bodies were characterised by SDS-PAGE and they havebeen shown to be essentially intact as they migrate at the appropriatesize (Figure not shown).

2.3 Affinity and Specificity of i-Body Binding to CXCR4

The i-body ADCX-99 was shown in a BIAcore assay to bind to immobilisedCXCR4 positive lipoparticles (A), but showed very little binding to nulllipoparticles (B) or to lipoparticles that were positive for the GPCRCCR5 (C), demonstrating the specificity of the i-body ADCX-99 to CXCR4(FIG. 5).

The affinity of one CXCR4 i-body identified, ADCX-99 was approximatelyK_(D) of 600 nM (622.877 nM) to the CXCR4 positive lipoparticlesdetermined by Biacore assay in FIG. 5.

The i-body ADCX-272 was shown in a BIAcore assay to bind to immobilisedCXCR4 positive lipoparticles (FIG. 2), but showed very little binding tonull lipoparticles or to lipoparticles that were positive for the GPCRCCR5 via ELISA (FIG. 7B), demonstrating the specificity of the i-bodyADCX-272 to CXCR4.

The affinity of CXCR4 i-body ADCX-272 was determined to be approximatelyK_(D) 1.6 uM to the CXCR4 positive lipoparticles determined by Biacore(FIG. 2B).

Example 3—Affinity Maturation of i-Bodies

The i-body ADCX-99 was affinity matured using error prone PCR. This wascarried out in two ways; either by creating a library of randommutations directed to the CDR1 and CDR3 or using an average of 2-3nucleotide mutations anywhere in the sequence. The library was pannedaccording to Henderson et al. (2007) Structure 15:1452-66. Using thisstrategy, the i-body ADCX-99 was modified in the CDR1 and/or the CDR3regions to improve the affinity or expression to create a library ofmutants.

3.1 Improvement to Expression Levels, Affinity and Specificity ofi-Bodies

Ninety random mutant i-bodies of the affinity matured ADCX-99 werecultured in a 96 well plate. Analysis of periplasmic fractions showedprotein expression and affinity levels varied significantly among themutant clones. By comparison with ADCX-99, several mutant clones werebetter expressers than the wild-type ADCX-99 i-body (FIG. 6).

When the same ninety clones were then examined for binding to CXCR4positive lipoparticles it was observed that, although most of the cloneshad lower affinity for CXCR4 positive lipoparticles, several clonesshowed higher affinity (FIG. 7-1). Mutant i-body clones 36 and 39appeared to have higher binding to CXCR4 positive lipoparticles in thisassay compared to the wild-type ADCX-99 i-body. The mutant i-body cloneswere also examined for binding to CCR5 positive lipoparticles (FIG.7-2). I-body mutant clones 36 and 39 had the same low binding for CCR5as the wild-type ADCX-99 (FIG. 7-2) demonstrating specificity for CXCR4.

The mutant clones of ADCX-99 were subject to a further round of affinitymaturation and over 1000 mutant clones examined for improved affinityand expression.

The consensus sequence of the affinity matured i-bodies is shown in FIG.1D (SEQ ID NO:39). The CD1 and CDR3 regions are represented by SX₁SX₂X₃Rand Y′₁ RY′₂GY′₃YRHRY′₄LY′₅LG respectively.

The affinity matured i-bodies of the disclosure comprise a scaffoldregion which corresponds to amino acid resdiues 1 to 26, 33 to 79 and 88to 97 of SEQ ID NO:1 or a sequence at least 60% identical thereto orotherwise may comprise between one and five amino acid additions orsubstitutions. In one example, the polypeptide comprises the sequenceset forth in SEQ ID NO:2 or the sequence set forth in SEQ ID NO:2comprising between 1 and 5 amino acid additions or substitutions.

In one example A′ and B′ in SEQ ID NO:39 are any amino acid residue.

In one example, A′ in SEQ ID NO:39 is amino acid Q or K and B′ in SEQ IDNO:39 is amino acid residue V or A. In a further example, A′ is Q and B′is V or A in SEQ ID NO:39.

In one example, Z is absent or an amino acid selected from M, EAEA, MAor MP. A summary of the affinity matured sequences with improvements isdescribed in Table 2.

TABLE 2 Summary of sequences derived from ADCX-99generated by two rounds of affinity maturationOriginal CXCR i-body Binder ADCX-99 LQVDIVPSQGEISVGESKFFLCQVAGSGSDIRISWFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNAN IDDAGIYKCVVYRTGGYRHRALVLGEATVNVKIFQ (SEQ ID NO: 11) Affinity Maturation Round 2 Sequences AM3-114LQVDIVPYQGEISVGESKFFLCQVAGSLSGIRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVWRTGGYRHRYLVLGEATVNVKIF Q (SEQ ID NO: 40) AM3-920LQVDIVPSQGEISVGESKFFLCQVAGSGSGIRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVWRTGGYRHRYLVLGEATVNVKIF Q (SEQ ID NO: 44) AM4-1121LQVDIVPSQGEISVGESKFFLCQVAGSKSGIRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVYRTGGYRHRYLRLGEATVNVKIF Q (SEQ ID NO: 48) AM4-613LQVDIVPSQGEISVGESKFFLCQVAGSKSDVRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVWRTGGYRHRYLVLGEATVNVKIF Q (SEQ ID NO: 52) AM3-523LQVDIVPSQGEISVGESKFFLCQVAGSGSHMRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVWRVGGYRHRALVLGEATVNVKIF Q (SEQ ID NO: 56) AM4-661LQVDIVPSQGEISVGESKFFLCQVAGSKSDFRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVYRTGGYRHRYLVLGEATVNVKIF Q (SEQ ID NO: 60) AM3-466LQVDIVPSQGEISVGESKFFLCQVAGSGSHQRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVWRTGAYRHRALVLGEATVNVKIF Q (SEQ ID NO: 64) AM5-245LQVDIVPSQGEISVGESKFFLCQAAGSGSHIRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVWRTGGYRHRALVLGEATVNVKIF Q (SEQ ID NO: 68) AM4-272LQVDIVPSQGEISVGESKFFLCQVAGSYSDYRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVYRIGGYRHRYLVLGEATVNVKIF Q (SEQ ID NO: 72) AM4-746LQVDIVPSQGEISVGESKFFLCQVAGSKSNIRIS WFSPNGEKLTPNQQRISVVWNDDSSSTLTIYNANIDDAGIYKCVVYRTGGYRHRYLKLGEATVNVKIF Q (SEQ ID NO: 76) A summary of theamino acid positions modified relative to the consensus sequence ofADCX-99 (SEQ ID NO: 2 and 39) is shown in FIG. 1. FIG. 8 indicates theparticular amino acid residue substitutions corresponding to eachaffinity matured i-body. Underlining corresponds to the CDR1 and CDR3regions in each sequence.Table 3 summarises improvements in relation to the off-rates of the toptwenty affinity matured i-bodies for CXCR4 expressed on lipoparticles.

TABLE 3 Kd values for twenty affinity matured i-bodies Amino acid changecompared to ADCX99 CDR1 CDR3 Kd AM3-114 SLSGIR WRTGGYRHRYLVLG 0.0066 (SEQ ID (SEQ ID NO: 41) (SEQ ID NO: 42) 40) AM3-466 SGSHQRWRTGAYRHRALVLG 0.00784 (SEQ ID (SEQ ID NO: 65) (SEQ ID NO: 66) 64)AM3-920 SGSGIR WRTGGYRHRYLVLG 0.00817 (SEQ ID (SEQ ID NO: 45)(SEQ ID NO: 46) 44) AM4-661 SKSDFR YRTGGYRHRYLVLG 0.00955 (SEQ ID(SEQ ID NO: 61) (SEQ ID NO: 62) 60) AM3-523 SGSHMR WRVGGYRHRALVLG0.00998 (SEQ ID (SEQ ID NO: 57) (SEQ ID NO: 58) 56) AM4-774 SKSVIRYRTGGYRHRYLVLG 0.0105  (SEQ ID NO: 83) (SEQ ID NO: 84) AM4-1121 SKSGIRYRTGGYRHRYLRLG 0.1153  (SEQ ID (SEQ ID NO: 49) (SEQ ID NO: 50) 48)AM4-613 SKSDVR WRTGGYRHRYLVLG 0.01236 (SEQ ID (SEQ ID NO: 53)(SEQ ID NO: 54) 52) AM4-208 SKSEIR YRTGGYRHRYLVLG 0.01283(SEQ ID NO: 85) (SEQ ID NO: 86) AM4-1088 SKSDFR RTGGYRHRYLKLG 0.01349(SEQ ID NO: 87) (SEQ ID NO: 88) AM4-239 AYSDIR YRTGGYRHRYLVLG 0.01356(SEQ ID NO: 89) (SEQ ID NO: 90) AM3-32 SGSGIT WRTGVYRHRALVLG 0.0136 (SEQ ID NO: 91) (SEQ ID NO: 92) AM5-245 SGSHIR WRTGGYRHRALVLG 0.01445(SEQ ID (SEQ ID NO: 69) (SEQ ID NO: 70) 68) AM4-757 SKSAIRYRTGSYRHRYLVLG 0.01488 (SEQ ID NO: 93) (SEQ ID NO: 94) AM4-386 ITSEGHETTVFNEVMRLGNG 0.015   (SEQ ID NO: 95) AHVY (SEQ ID NO: 96) AM4-352SKDDIR YRTGGYRHRYLVLG 0.0152  (SEQ ID NO: 97) (SEQ ID NO: 98) AM3-182VGNHIR WRAGGYRHRALVLG 0.01562 (SEQ ID NO: 99) (SEQ ID NO: 100) AM4-203SYGDIR YRTGGWRHRYLVLG 0.01621 (SEQ ID NO: 101) (SEQ ID NO: 102) AM4-272SYSDYR YRIGGYRHRYLVLG 0.01631 (SEQ ID (SEQ ID NO: 73) (SEQ ID NO: 74)72) AM5-95 SGSHIR WRTGGYRHRALVLG 0.01663 (SEQ ID NO: 103)(SEQ ID NO: 104)Table 4 summarises the affinity (Ka, Kd and K_(D)) of the top twentyaffinity matured i-bodies for CXCR4 expressed on lipoparticles.

TABLE 4 Affinity of CXCR4 binding polypeptides for CXCR4 expressed onlipoparticles Binding Affinity to CXCR4 expressed on lipoparticlespolypeptide Ka (M⁻¹ s⁻¹) Kd (M⁻¹ s⁻¹) KD (nM) AM3-114 1.297 × 10⁶  6.29× 10³ 4.85  1.9 × 10⁶  6.34 × 10³ 3.33 AM3-523 1.003 × 10⁶  8.61 × 10³8.53  9.65 × 10⁵  9.15 × 10³ 9.47 AM3-466  4.65 × 10⁵  6.43 × 10³ 13.83 4.26 × 10⁵  6.67 × 10³ 15.7 AM3-920 1.117 × 10⁶  8.02 × 10³ 7.18  1.26× 10⁶  7.41 × 10³ 5.87 AM4-613 1.334 × 10⁶ 10.44 × 10³ 7.83  AM4-11211.289 × 10⁶  9.29 × 10³ 7.21  1.42 × 10⁶  9.54 × 10³ 6.7 AM4-661  9.66 ×10⁵  9.21 × 10³ 9.53  9.83 × 10⁵  9.5 × 10³ 9.66 AM5-245  8.13 × 10⁵ 12.1 × 10³ 14.88  7.71 × 10⁵  12.3 × 10³ 15.9 AM4-272  8.06 × 10⁶ 13.08× 10³ 1.6 AM4-746  2.5 × 10⁶ 13.39 × 10³ 5.36

The specificity of the affinity matured binders in Table 4 wasdetermined against a number of chemokines and is shown in FIG. 9demonstrating high specificity for the target CXCR4 and limited bindingto other chemokine G-protein coupled receptors (GPCRs).

3.2 Improvement to Expression Levels, Affinity and Specificity ofAffinity Matured i-Bodies

Improvement in expression from 10 mg/L to 14 mg/L was observed when aG>K amino acid substitution at position 28 and an I>F amino acidsubstitution at position 31 were made to (designated X₁ and X₃respectively in FIG. 1D) within the CDR1 of ADCX-99 and an A>Y aminoacid substitution was made at position 89 (designated Y₄ in FIG. 1D)within the CDR3 of the ADCX-99 sequence. This is represented by thesequence corresponding to AM4-661. The alignment of AM4-661 againstADXC-99 is shown in FIG. 10A.

An improvement in affinity for CXCR4 from >700 nM to 1 nM was seen whena G>Y substitution at position 28 (designated X₁ in FIG. 1D), and I>Ysubstitution at position 31 (designated X₃ in FIG. 1D) were made in theCDR1 of ADCX-99, and a T>I (designated Y₂ in FIG. 1D) in position 82 andA>Y substitution at position 89 (designated Y₄ in FIG. 1D) were made inthe CDR3 of ADCX-99, as evidenced by sequence corresponding to AM4-272.The alignment is shown in FIG. 10B.

An improvement in specificity for CXCR4 was observed for polypeptidesAM3-114, AM5-245 and AM3-523. CCR4 activity (determined by DiscoverXβ-arrestin assay) of 34% for ADCX-99 was reduced to −3%, −5% and −2% forAM3-114, AM5-245 and AM3-523 respectively. All three polypeptides had aY>W substitution at position 80 (designated Y₁ in FIG. 1D) in the CDR3of ADCX-99 and a D>G or H substitution at position 30 (designated X₂ inFIG. 1D) in the CDR1 of ADCX-99. The alignment is shown in FIG. 10C.

Example 4—Half-Life Improvement of i-Bodies 4.1 Dual Specificity toCXCR4 and Human Serum Albumin

A dual specificity i-body was generated by conjugating an 18-residuehuman serum albumin (HAS) binding peptide(N-terminus)-RLIEDICLPRWGCLWEDD-(C-terminus) (described in US20100104588; Dennis M S et al (2002) J. Biol. Chem. 277, 35035-35043) tothe C-terminus of AM3-114 to generate AM3-114-Im7-SA21 (SEQ ID NO: 80).The Im7 protein was used to facilitate detection of the conjugate.

Affinity for CXCR4 and HSA was measured by surface plasmon resonance asshown in FIG. 11. The bi-specific CXCR4 and HSA binder AM3-114-Im7-SA21demonstrated approximately 5-10 nM affinity for CXCR4 and approximately500 nM affinity for human serum albumin (HSA) (FIG. 11A). The affinityto CXCR4 was unchanged with and without the additional of the 18 residueHSA peptide SA21 (FIG. 11C and D respectively). The i-body AM3-114 didnot bind to HSA without the addition of the 18 residue HSA peptide SA21(FIG. 11B). Accordingly, the conjugate demonstrating specific binding toboth CXCR4 and HSA.

4.2 PEGylation of i-Bodies

AM3-114-Im7-FH and AM4-746-Im7-FH [Im7-FH corresponds to an N-terminalsolubility and purification tag wherein Im7 is an E. coli protein (HosseR J et al (2009) Anal Biochem 15; 385(2):346-57 and FH is flag+6 His]were conjugated to 30K linear or 2×20K branched PEG using asite-specific conjugation approach (HiPEG™ technology, PolyTherics, UK)in order to increase the hydrodynamic radius of the i-body molecules andthus reduce renal and hepatic elimination (Konterman et al 2011 CurrOpin Biotech 22:868-8760).

4.3 Evaluation of Half-Life Extended i-Bodies

The PEGylated material (AM3-114-30K PEG, AM3-114-2×20K PEG,AM4-746-2×20K PEG) and one HSA peptide conjugate (AM3-114-Im7-FH-SA21)were evaluated in a preclinical pharmacokinetic study in mice alongsidecontrol i-bodies ADCX99-9H (9 histidine tag) and AM3-114-Im7-FH(containing both the Im7 protein and FLAG+6 His tag). The test itemswere administered to groups of mice once by intravenous injectionadministration as described in Table 4 below:

TABLE 4 Test items administered to mice Dose Dose Number Concen- Dose ofGroup Level tration volume Animals Numbers Treatment (mg/kg) (mg/mL)(mL/kg) (Males) 1 ADCX99-9H 3 1 3.0 9 2 AM3-114-IM7- 3 1 3.0 9 FH 3AM3-114-Im7- 2 1 2.0 9 FH-SA21 4 AM4-746-2x20K 1.25 1 1.25 12 PEG 5AM3-114-30K 3 1 3.0 9 PEG 6 AM3-114-2x20K 1.25 1 1.25 12 PEGThe dose volume administered to animals in groups 1, 2 and 5 was 3mL/kg.The dose volume administered to animals in group 3 was 2 mL/kg.The dose volume administered to animals in groups 4 and 6 was 1.25mL/kg.A series of blood samples from all mice (0.3 mL, 2 time point/mouse3/group/time point) were collected following dosing as follows:

TABLE 5 Timing of blood sampling from mice Group Number Timepoints 1 5,15, 45, 60 and 90 minutes 2 5, 15, 45, 60 and 90 minutes 3 5 minutes and2, 6, 12 hours and 1 and 3 days 4 5 minutes and 2, 6, 12 hours and 1 and3, 5 and 6 days 5 5 minutes and 2, 6, 12 hours, 1 and 3 days 6 5 minutesand 2, 6, 12 hours and 1, 3, 5 and 6 days

For this purpose, each mouse (CD-1 mouse) was bled via the saphenousvein or under isoflurane anaesthesia by cardiac puncture and the samplescollected into tubes containing the anticoagulant, K₂-EDTA. Tubes wereplaced on wet ice pending processing. Following its last blood sampling,each animal was euthanized by cervical dislocation and discarded withoutfurther examination.

Following collection, the samples were centrifuged (approximately 4° C.)and the resulting plasma was recovered in two separate aliquots andstored frozen (60° C.) in labeled Protein LoBind 1.5 mL tubes(Eppendorf, cat no. 022431081). The ADCX99-9H, AM3-114-IM7-FH,AM3-114-Im7-FH-SA21, AM4-746-2×20K PEG, AM3-114-30K PEG andAM3-114-2×20K PEG concentrations were determined by an LC-MS/MS assaymethod. Sample pre-treatment involved the direct tryptic digestion ofADCX99-9H, AM3-114-IM7-FH, AM3-114-Im7-FH-SA21, AM4-746-2×20K PEG,AM3-114-30K PEG and AM3-114-2×20K PEG to a signature peptide (sPeptide)from CD-1 mouse plasma; GEKLTPNQQRIG was used as the internal standard.The compounds were identified and quantified over a theoreticalconcentration range of 0.500 μg/mL to 100.000 μg/mL for ADCX99-9H,AM3-114-IM7-FH, AM3-114-Im7-FH-SA21, AM3-114-30K PEG and AM3-114-2×20KPEG and 0.083 μg/mL to 16.667 μg/mL for AM4-746-2×20K PEG. Stocksolutions of ADCX99-9H, AM3-114-IM7-FH, AM3-114-Im7-FH-SA21,AM4-746-2×20K PEG, AM3-114-30K PEG and AM3-114-2×20K PEG were stored at−80° C. nominal and GEKLTPNQQRIG internal standard was stored at 4° C.

An AB Sciex API 5000 or QTRAP 5500 quadrupole mass spectrometer using aTurbo ionspray was used for the detection of ADCX99-9H, AM3-114-IM7-FH,AM3-114-Im7-FH-SA21, AM4-746-2×20K PEG, AM3-114-30K PEG andAM3-114-2×20K PEG.

The half-life of the AM3-114 i-body was extended by the addition of boththe SA21 HSA-binding peptide and by the addition of PEG 30K and PEG2×20K as demonstrated in FIG. 12, and Table 6A and 6B.

TABLE 6A Pharmacokinetic Parameters Following Intravenous Injection inCD-1 Mice, AAT-M4-438 (1 of 2) AUC_(0-T) C_(max) AUC_(0-T) (SE) C₀T_(max) C_(max) (SE) (ug * h/ (ug * h/ Formulation Gender (ug/mL) (h)(ug/mL) (ug/mL) mL) mL) ADCX99-9H/3 mg/kg Male 20.871 0.08 13.611 3.0835.318 0.403 AM3-114-IM7-FH/3 mg/kg Male 40.820 0.08 16.275 2.107 4.7500.297 AM3-114-Im7-FH-SA21/2 mg/kg Male 23.284 0.08 20.531 1.024 25.2661.114 AM4-746-2 × 20K PEG/1.25 mg/kg Male 26.168 0.08 25.559 2.023175.057 8.650 AM3-114-30K PEG/3 mg/kg Male 78.799 0.08 76.652 1.508495.670 16.804 AM3-114-2 × 20K PEG/1.25 mg/kg Male 25.652 0.08 25.4422.267 380.960 23.559

TABLE 6B Pharmacokinetic Parameters Following Intravenous Injection inCD-1 Mice, AAT-M4-438 (2 of 2) AUC_(0-∞) T_(last) λ_(Z) T_(half) V_(D)CI_(TOT) Formulation Gender (ug * h/mL) (h) (1/h) (h) (mL/kg) (mL/h/kg)ADCX99-9H (6H)/3 mg/kg Male 5.417 1.50 2.6660 0.26 207.739 553.838AM3-114-IM7-FH/3 mg/kg Male 4.767 1.50 3.8809 0.18 162.155 629.303AM3-114-Im7-FH-SA21/2 mg/kg Male 25.544 6.00 0.7279 0.95 107.571 78.296AM4-746-2 × 20K PEG/1.25 mg/kg Male 175.834 72.00 0.0674 10.29 105.5357.109 AM3-114-30K PEG/3 mg/kg Male 499.831 72.00 0.0585 11.85 102.6186.002 AM3-114-2 × 20K PEG/1.25 mg/kg Male 381.849 144.00 0.0360 19.2490.854 3.2744.4 Fusion of XTEN Protein Sequence with i-Bodies

As an alternative to PEGylation the inventors examined the utility ofthe XTEN approach which utilises the addition of roughly 400 residues ofquasi-repeat sequence to the i-body, to increase the half-life of i-bodyin vivo, followed by a C-terminal His tag for purification/detection.The XTEN sequence is engineered to be intrinsically unstructured andtherefore non-immunogenic, and is also highly hydrophilic which shouldaid with the solubility and stability of the i-bodies duringexpression/purification/downstream applications (Schellenberger et al,(2009) Nature Biotech; 27(12): 1186-1190).

AM3-114 was cloned into a bacterial expression vector (pET26) andinitial expression trials were performed. Western blotting shows a bandthat was reactive to anti-His antibody, which is not present in thenon-induced control, strongly suggesting that the AM3-114-XTEN constructis indeed being expressed. The predicted MW of the AM3-114-XTENconstruct is roughly 50 kDa, whereas the band of interest is at anapparent MW of just over 100 kDa (data not shown). This is consistentwith the expected mobility shift due to the highly unstructured andacidic XTEN group causing a significant decrease in the electrophoreticmobility of the ibody, a phenomenon that has previously been observedfor other unstructured proteins.

This material was tested for binding to CXCR4 on RAMOS cells by FlowCytometry and shown to bind in a dose dependant fashion. Binding wasonly slightly less than for the AM3-114 i-body, indicating that the114-XTEN was active. AM3-114-XTEN was tested in SPR and found that itstill retained binding to CXCR4 on lipoparticles albeit at a slightlyreduced affinity. Interestingly the lower affinity appears to be dueprimarily to the on rate as the off rate is similar to the i-bodywithout XTEN (data not shown).

4.5 PASylation of i-Bodies

Another method of extending the half-life of the i-body is to use thePASylation technology. The i-body will be genetically fused with apolypeptide sequence that consists of several hundred residues of thesmall amino acids proline, alanine, and/or serine (“PAS”). These PASsequences, particularly the PAS(400) and PAS(600) adopt a random coilstructure in aqueous solution thus generating a large hydrodynamicvolume that allows for extension of the half-life of the protein inblood, proteins fused with these sequences have also reported to havevery low immunogenicity and toxicity, (Schlapschy et al. Protein Eng DesSel (2013) 26:489). These sequences when fused to a target protein havebeen shown to extend the half-life in mice, and to improve the drug likequalities of the target protein.

The i-body will be fused to the PAS sequence at the C-terminus andprotein expressed in E. Coli.

Example 5—Functional Characteristics of the i-Bodies

5.1 Modulation of cAMP on CXCR4 Transfected Cells

DiscoveRx has developed a panel of cell lines stably expressingnon-tagged GPCRs that signal through cAMP. Hit Hunter® cAMP assaysmonitor the activation of a GPCR via an inhibitory regulative G-protein(Gi) and a stimulative regulative G-protein (Gs) secondary messengersignaling in a homogenous, non-imaging assay format using a technologydeveloped by DiscoveRx called Enzyme Fragment Complementation (EFC) withβ-galactosidase (β-Gal) as the functional reporter. The enzyme is splitinto two complementary portions: EA for Enzyme Acceptor and ED forEnzyme Donor. ED is fused to cAMP and in the assay competes with cAMPgenerated by cells for binding to a cAMP-specific antibody. Active β-Galis formed by complementation of exogenous EA to any unbound ED-cAMP.Active enzyme can then convert a chemiluminescent substrate, generatingan output signal detectable on a standard microplate reader.

Methods Cell Handling

cAMP Hunter cell lines were expanded from freezer stocks according tostandard procedures. The cells were then seeded in a total volume of 20μL into white walled, 384-well microplates and incubated at 37° C. forthe appropriate time prior to testing. cAMP modulation was determinedusing the DiscoveRx HitHunter cAMP XS+ assay according to manufacturer'sinstructions.

Antagonist Format

For antagonist determination, the Hunter cells which express CXCR4 werepre-incubated with sample followed by agonist challenge at the EC80concentration. (For Gi cAMP assays, a forskolin concentration of 15 μMwas used). Media was aspirated from cells and replaced with 10 μL 1:1HBSS/Hepes:cAMP XS+ Ab reagent. 5 μL of 4× stock of AMD3100 or i-bodiesto CXCR4 were added to the cells and incubated at 37° C. or roomtemperature for 30 minutes. 5 μL of 4× EC80 agonist SDF-1 was added tocells and incubated at 37° C. or room temperature for 30 or 60 minutes.For Gi coupled GPCRs, EC80 forksolin was included (a forskolinconcentration of 15 μM was used).

Signal Detection

After appropriate compound incubation, assay signal was generatedthrough incubation with 20 μL cAMP XS+ ED/CL lysis cocktail for one hourfollowed by incubation with 20 μL cAMP XS+ EA reagent for three hours atroom temperature. Microplates were read following signal generation witha PerkinElmer Envision™ instrument for chemiluminescent signaldetection.

Results

Inhibition of cAMP by control i-body (21H5), AMD3100 and i-bodiesAM3-114, AM4-272, AM3-523, AM4-746, AM4-1121 (1050) was then determined.The data is show in Table 7 and FIG. 13. Chemokine receptors such asCXCR4 are primarily Gai-coupled and therefore, signal via 2nd messengercAMP. Regulation of cyclic AMP (cAMP) might be important forinteractions between SDF-1 and various cellualar signalling. The panelof CXCR4 i-bodies was examined for the ability to modulate cAMP levelsin vitro. The previously described antagonist AMD3100 displayed adose-dependent effect inhibition of cAMP with an expected 1050 of 615nM. The i-bodies were very effective at blocking the SDF-1 induceddecrease in cAMP in these cells. Indeed, all i-bodies had 1050 valueslower than AMD3100. Based on the 1050 results, the CXCR4-binding i-bodyAM3-114 is a potent inhibitor of cAMP.

These data suggest that the i-bodies can bind to CXCR4 and inhibit keyfunctional signalling such as Gai-signaling pathway, which controls cAMPmodulation without blocking the Gq-pathway that influences calcium flux.This could be the reason why the i-bodies could block inflammation andfibrosis but not mobilise stem cells which would be an advantage whenused in long term therapy.

TABLE 7 IC₅₀ of compounds to CXCR4 determined by cAMP assay inantagonist mode cAMP inhibition Sample IC50 (nM) 21H5 (controli-body) >10 uM AMD3100 615 AM3-114 99  AM4-1121 125 AM3-523 225 AM4-746115 AM4-272 300

5.2 Modulation of Calcium on CXCR4 Transfected Cells

CXCR4 transfected cells were treated with i-bodies or AMD3100 for 30min, then stimulated with 100 ng/ml of SDF-1 for 30 min. Inhibition ofCa2+ influx by controls or i-bodies (IC₅₀) was then determined.

Materials Cells

Mammalian cells stably expressing human CXCR4 receptor were producedin-house by Multispan, Inc (catalog no. C1004-1). Control agonist usedwas SDF-1 (Peprotech, Cat#300-28A).

Compounds

7 compounds/i-bodies (21H5, AM3-114, AM4-272, AM3-523, AM4-746,AM4-1121, and AMD3100) were tested in liquid form at 40 uM or 10 mM.AMD3100 (also known as plerixafor or Mozobil) is a small moleculeantagonist of CXCR4 and is available commercially. It was used as apositive control.

Calcium Assay Kit

Screen Quest™ Fluo-8 No Wash kit (AAT Bioquest, Cat#36315)

Instruments

FLIPR 384 (Molecular Devices)

Methods Calcium Assay

Cells were seeded in 384-well plate at an appropriate density andcultured overnight. Calcium assay was conducted according to themanufacturer's protocols. The calcium dye loading buffer was added tothe cells and incubated for one hour at 37° C. Calcium flux wasmonitored for 120 seconds with compound injected into the wells at 19thsecond. In antagonist mode, carrier or compounds were preincubated withthe cells for 30 minutes before calcium flux measurement with thecontrol agonist at EC80 concentration obtained from dose-response curve.The data are shown in Table 8 and FIG. 14. Since Calcium flux isdirected by the Gq pathway, this results suggests that all i-bodiestested do not significantly modulate the Gq pathway. Accordingly, thei-bodies do not modulate calcium flux.

TABLE 8 Calcium Inhibition Assay Calcium Inhibition EC50 (nM) 21H5 >10uM AMD3100 500 nM AM3-114 uM  AM4-1121 uM AM3-523 uM AM4-746 uM AM4-272uM

5.3 Modulation of β-Arrestin on CXCR4 Transfected Cells

Binding of the i-bodies to CXCR4 were examined in a β-Arrestin BRETassay as described in See, Heng B et al (2011) Assay and DrugDevelopment Technologies 9(1):21-30. The i-bodes were examined at tenconcentrations with and without 100 nM SDF-1 with the addition of‘vehicle’ and ‘SDF-1+vehicle’ controls in order to characterise if thei-bodies are agonist or antagonists of CXCR4 activity.

The results of the β-Arrestin BRET assay for each binder is provided inTable 9 and in FIG. 15. AMD3100 had an 1050 of 18 nM whilst the parentCXCR4 i-body, ADCX-99, had a very weak effect on β-arrestin recruitment,probably due to the low affinity (643 nM) for CXCR4 as shown by SPR. Thei-body panel 1050 values ranged between 164 nM for AM3-114 and 127, 13nM for AM3-523. These changes in β-arrestin recruitment are as a resultof changing 1-10 amino acids in the binding regions.

TABLE 9 Affinity of i-bodies determined by β-Arrestin assay IC50 (nM) inβ-Arrestin BRET assay (Antagonist mode in the presence Protein of 100 nMSDF-1) 23B2 No activity AMD3100 18 mAb-12G5 64 SDF-1 NA ADCX-99 Noactivity AM1-126 610 AM1-320 1419 AM3-114 164 AM3-920 ~uM  AM4-1121 796AM4-613 1826 AM3-523 12713 AM4-661 1544 Am3-466 6322 AM5-245 ~uM AM4-272861 AM4-746 741

Example 6—Binding Characteristics of the i-Bodies

Any cell that expresses human CXCR4 on the surface can be used toexamine the ability of the CXCR4 binding molecules or polypeptides(i-bodies) described herein to bind native, cell surface CXCR4. Examplesof such cell lines include the human T cell line, CEM, as well as othercell lines such as Ramos, Raji, Namalwa, L540, DMS79, MDA-MB-231,MDA-MB-361, MDA-MB-549, MOLT-4, DU-4475, DU-145, PC3, LNcaP, SW480,HT29, NCI-H69 and HL60.

6.2 In Vitro Binding Affinity of i-Bodies by Flow Cytometry Analysis

Cells were treated with i-bodies AM3-114, AM4-272, AM3-523, AM4-746 andAM4-1121 (10 μM, 1 μM and 0.001 μM), and the staining intensities wereevaluated by flow cytometry analysis. Cell lines tested were T47D (CXCR4negative), MDA-MB-231 (low CXCR4 expression) and Namalwa, NCI-H69,Jurkat, CCRF-CEM, A498, Ramos (high CXCR4 expression).

Method

Cell Lines were harvested and transferred cells to 96-well tissueculture plates (2×10⁵ cells/well). The culture plate was thencentrifuged at 1000 rpm, 4° C. for 5 min. Cells were resuspended with100 uL of PBS buffer containing test antibody and incubated at 4° C. for60 min. Cells were washed with 300u1 ice-cold FACS buffer twice, 1000rpm, 5 min and resuspended with 100 ul of PBS buffer containinganti-His-PE antibody (for i-bodies) and incubated at 4° C. for 40 min indark. Cells were then washed with 300 uL ice-cold FACS buffer×2, 1000rpm, 5 min and the cells resuspended with 300 ul of suspension bufferand subject to FACS analysis according to standard methods.

Binding affinity for CXCR4 demonstrated by flow cytometery analysis isshown in FIGS. 16-1 to 16-3 for representative i-body AM3-114 on T47Dcells (A), Namalwa cells (B), MOLP8 (C), MOLT4 (D), Jurkat cells (E),CCRF-CEM (F), A498 (G), Ramos (H), NCI-H69 (I), and HL-60 (J). Celllines were tested with three i-body concentrations, (10 μM, 1 μM and0.001 μM) with the exception of Namalwa cells which were also testedwith i-bodies at 4.7, 2.1, 0.47, 0.21, 0.1 and 0.01 μM.

Example 7—Competition with SDF-1 Binding to CXCR4 by the i-Bodies

7.1 SPR Assay of Competition for i-Bodies Binding to CXCR4

Competition studies were performed to determine the ability of thei-bodies to inhibit binding of SDF-1 to CXCR4 utilising CXCR4 containinglipoproteins (IntegraMolecular) as described in WO 2005/042695.

A panel of CXCR4 i-bodies were tested by surface plasmon resonance (SPR)for their ability to compete with the ligand SDF-1. FIG. 17 shows anexample of two i-bodies, one which competed with SDF-1 in a dosedependant manner (AM3-114 FIG. 17A) and one which did not compete well(AM4-272 FIG. 17B). CXCR4 lipoparticles were co-injected with i-body andSDF-1 at 2 nM 50 nM and 200 nM.

Table 12 shows the extent (indicated by +) of each i-body to competewith SDF-1 for binding to CXCR4 positive lipoparticles.

TABLE 12 Extent of competition with SDF-1 for binding to CXCR4 positivelipoparticles i-body Competition with SDF-1 AM4-661 + AM3-466 ++ AM3-114+++ AM4-272 +/− AM3-523 ++ AM4-746 ++  AM4-1121 ++ AM3-920 ++ AM3-126 −7.2 Flow Cytometry Assay of Competition for i-Bodies Binding to CXCR4 byVarious CXCR4 Binding Molecules

The binding of CXCR4 i-bodies (AM3-114-6H, AM4-272-6H and AM3-523-6H)containing the N-terminal sequence EAEA to CXCR4 expressed on thesurface of cells and the ability of SDF-1 to compete for the binding wasassessed using flow cytometry. The i-bodies were incubated with Ramoscells in 100 μl of FACS buffer (1×PBS & 2% FCS) at 4° C. for 60 minutes.After washing twice with 2 ml of ice cold FACS buffer, cells werecentrifuged at 1,500 rpm for 5 mins, cells were resuspend in 100 μl ofFACS buffer containing the anti-His-PE antibody (MACS Molecular, Orderno: 130-092-691) and incubated at 4° C. for 40 mins in the dark. Thisassay is robust and can be used to examine competition between thei-bodies and SDF-1 and other antagonists. In this case each i-body (0.5μM) is incubated with the cells either alone or in the presence of anexcess of SDF-1 (2 μM), MAb12G5 (2 μM), and AMD3100 (2 μM). The bindingof all three i-bodies was reduced upon the addition of 2 μM AMD3100(FIG. 18). SDF-1 was able to compete well with AM4-272 but onlypartially with AM3-114 and AM3-523. All three i-bodies were competedwith AMD3100 indicating that there is similarity between the bindingsite for the i-bodies and this small molecule. The anti-CXCR4 MAb 12G5,was able to reduce the binding of 523 almost completely and to partiallyblock the binding of AM3-114 and AM4-272.

Example 8—Inhibition of Migration of CXCR4 Expressing Cells by thei-Bodies

The ability of the CXCR4 binding molecules or polypeptides disclosedherein (i-bodies) to inhibit migration induced by SDF-1 can be examinedusing breast cancer cells line MDA-MB-468 and prostate cancer cell linePC3 which are well characterised in terms of their metastatic potentialand properties both in vitro and in vivo (Kaighn et al 1979 Invest Urol.17(1):16-23. Yoneda et al 2000 Cancer 88:2979-88). MDA-MB-468 cells areinvasive and metastasise to lung from the primary mammary fat padtumours of nude mice. The method is described in Byeong-Chel Lee et al(2004) Mol Cancer Res 2; 327. Briefly, the cells are added tofibronectin (50 pg/mL)-coated transwell inserts (Costar Corp.,Cambridge, Mass.). The MDA-MB-468 cells and PC3 cells are then starvedovernight in serum-free media and would then be incubated with theanti-CXCR4 i-body before their application to 8-μm-pore-size transwellinserts. Cells are suspended into the upper chamber at a finalconcentration of 7×10⁴/mL in 500 μL of RPMI 1640. Serially dilutedrecombinant SDF-1 is added to the lower chamber. After 3 to 9 hours ofincubation, the cells on the upper surface of the filters are removed bywiping with cotton swabs, and the migrated cells on the lower chamberare fixed and stained using a Hema3 kit (Biochemical Sciences Inc.,Swedesboro, N.J.), according to the manufacturer's instructions.Cellular transmigration is then enumerated in four separate microscopicfields per field (Kashima et al Cancer Sci 105 (2014) 1343-1350; Zhu etal Molecular Cancer Research (2013) 11(1) 86-94).

Example 9—Inhibition of Angiogenesis by the i-Bodies

Inactivation of surface SDF-1 or CXCR4 in HUVECs impairs the ability ofHUVECs to align into tubular structures on Matrigel-coated surfaces. Thei-bodes of the present disclosure can be tested for their effects on theability of HUVECs to form Matrigel-dependent tubular structures as perLiang et al, Biochem Biophys Res Commun. 2007 August 3; 359(3): 716-722.To perform the capillary tube formation assay, CXCR4 i-body antagonistis pre-incubated with human umbilical vein endothelial cells (HUVEC) at100 nM, 5 μM, and 1 μg/ml concentrations, respectively, for 10 min atroom temperature before seeding. The cells are then plated onto thelayer of Matrigel at a density of 1×10⁵ cells/ml of M199 medium with 1%FBS and 200 ng/ml of SDF-1. After 18 hrs, the wells are photographed at4× magnification in five randomized fields and the number of theirtubular networks is counted.

Example 10—Inhibition of Tumor Cell Proliferation In Vitro by i-Bodies

The ability of the CXCR4 molecules or polypeptides disclosed herein(i-bodies) to inhibit proliferation of Ramos tumor cells, a humanBurkitt's lymphoma cell line expressing CXCR4 mentioned above, in vitrowas examined in a MTT cell proliferation assay as described in (Lapteva(2005) Cancer Gene Therapy 12, 84-89). Cells were grown in a 96-welltissue culture plate and treated with a vehicle or the anti-CXCR4i-body. The cells were then incubated with the MTT solution forapproximately 4 hours. After this incubation period, a water-insolubleformazan dye is formed. After solubilization, the formazan dye isquantitated using a scanning multi-well spectrophotometer (ELISAreader). The absorbance revealed directly correlates to the cell number.

It was found that i-body AM3-114 at 10 μM was able to substantiallyinhibit the growth of RAMOS cells. This effect was particularly obviousbetween 24 and 48 hrs after addition of the i-body, although there wasstill substantial inhibition of cells at 72 hrs after i-body addition.As expected AMD3100 was also able to inhibit cell growth in this timeframe. Two control i-bodies (21H5 and AM8-7) had little effect on cellgrowth. There was a small inhibitory effect of i-body AM4-272 butAM3-523 had no observable effect in this assay. The i-bodies had noeffect on normal HEK cells.

Example 11—Induction of Apoptosis by the i-Bodies

The ability of an i-body of the invention to induce apoptosis in Ramostumor cells (a human Burkitt's lymphoma cell line) was examined in anapoptosis assay according to the methods as described in Mishra M et al(2011) J Cell Mol Med 15(11):2462-77. I-bodies were incubated with Ramoscells and examined by flow cytometry after 24 or 72 hours. The cellswere stained for annexin V and propidium iodide which are classicmarkers for apoptosis. Cells which were double positive were assessed tohave become apoptotic. The three CXCR4 bodies (AM3-114-6H, AM4-272-6Hand AM3-523-6H) were able to strongly induce apoptosis (FIG. 19).Untreated cells acted a negative control to show that the cells wereotherwise healthy. Thapsigargin is a well-described inducer ofapoptosis, and shows the expected level of apoptosis. AMD3100 does notinduce significant apoptosis in Ramos cells. This is consistent with aprevious report showing that the human anti-CXCR4 mAb MDX-1338 was ableto induce apoptosis in Ramos cells but AMD3100 was not (Kuhne et al ClinCancer Res (2013) 19(2): 357-66).

Example 12—Binding of the i-Bodies to Tumours In Vivo

12.1—i-Body Staining of Tumours in the Spleens and Livers of SCID/BgMice that had been Intravenously Injected with CCRF-CEM Cells

Immunohistochemistry staining using the anti CXCR4 i-bodies (AM3-114-6H,AM4-272-6H and AM3-523-6H) at 130 μg/ml was carried out on the spleensand livers of SCID/bg mice that had been intravenously injected withCCRF-CEM cells and sacrificed after 27 days. Tissues were fixed in 10%neutral buffered formalin overnight and subsequently transferred intotissue cassettes and placed in 70% ethanol. The tissues were thenparaffin embedded. Slides containing 4 μm sections were deparaffinizedand hydrated by incubating them in two changes of xylene for five mineach, followed by two changes of 100% ethanol for 3 min each, 70%ethanol for 2 min, 50% ethanol for 2 min, and distilled water for 5 min.Antigen retrieval was performed by incubating the slides in 10 mM Citricacid solution (pH 6.0) in an 80° C. oven overnight. The slides weresubsequently washed in PBS and permeabilized in 10% methanol containing0.4% H₂O₂ for 30 min. After permeabilization, slides were stained withCXCR4 specific iBodies (AM3-114-6H, AM4-272-6H, or AM3-523-6H) and acontrol iBody (21H5-6H) overnight at 4° C. All slides were subsequentlystained with biotinylated anti-His tag antibodies (Miltenyi Biotech) anddeveloped using an HRP-DAB cell and tissue staining kit according to themanufacturer's instructions (R&D systems).

130 μg/ml of AM3-114-6H and AM4272-6H stained CCRF-CEM cells in thespleen and liver of the immunocompromised mice challenged with thesecells (Figure not shown).

12.2—Solid Tumors

The ability of the CXCR4 binding molecules or polypeptides (i-bodies) toinhibit proliferation of an established solid tumor in vivo can beexamined using a Ramos subcutaneous tumor cell model (or Namawala cellsor MDA-MB-231 or MDA-MB-468 or PC3 cells). In this assay, 10×10⁶cells/mouse are implanted into the flank region of each mouse andallowed to grow to a mean size of 40 mm³, calculated bylength×width×height/2 of the tumors. The mice then receive anintraperitoneal (ip) injection of a first dose of i-body (designated asday 0 of treatment) and a second ip dose of antibody on day 7. Groups ofmice are treated with either (i) vehicle (ii) i-body or (iii) anti-CD20positive control. Tumor volume and mouse body weight are measured atregular intervals (approximately 2-3 times/week) between day 0 and day30 post dosing.

This assay model can also be used to assess the ability of the i-bodesto increase survival time of the mice.

12.3—Metastasis

The anti-metastatic efficacy of the i-bodies of the present disclosurecan be tested in animal models. For breast cancer metastasis, MDA-MB-231cells are injected intravenously to generate an experimental metastasismodel. Six- to eight-week-old female nude mice are given injections of1.5×10⁶ MDA-MB-231 breast cancer cells mixed with the i-body (1 mM, lessthan 5 min preincubation) through the tail vein (10/group). From thefollowing day, mice in the treated group are given 4 mg/kg of the i-bodydaily by i.p. injection. The animals are sacrificed 35 days after thetumor cell injection. Whole lung tissues are harvested and sectioned forreal-time RT-PCR for human CXCR4 and H&E histostaining to evaluate themetastatic tumor area in five fields per section microscopically.

For the head and neck cancer animal model, metastatic subclones of686LN-Ms cells are injected in the same way as MDA-MB-231 cells asdescribed (Yoon Y et al., (2007) Cancer Res 67:7518-7524).

For the uveal melanoma micrometastasis mouse model, on day 0, each mouseis inoculated with 1×10⁶ wild-type OMM2.3 cells expressingHGF/TGF-b/CXCR4/MMP2 into the posterior chamber of right eye. On day 3,mice are treated with the i-body of the invention daily by i.p.injection, whereas the control mice are injected with 0.1 mL 45%(2-hydroxypropyl)-beta cyclodextrin. On day 7, eyes with tumor areenucleated. The growth of tumor is checked by histological methods. Onday 28, hepatic tissues are collected and fixed in 10% formalin,processed, H&E stained, and the number of hepatic micrometastasescounted under microscope. Six sections through the center of the liverare microscopically examined for the presence of micrometastases (100 mmdiameter) and the average number of micrometastases per sectiondetermined (Liang et al PLoS One. 2012; 7(4): e34038).

Example 13—Inhibition of HIV Invasion by i-Bodies

An in vitro HIV inhibition assay was used to demonstrate the ability ofi-bodes to inhibit HIV entry into CXCR4 expressing T-cells. AM3-114 wasable to block HIV entry into CXCR4 expressing T-cells with a similarefficacy as AMD3100 as shown in FIG. 20. AM3-114 and AMD-3100 had anIC₅₀ of 50 nM, whereas the negative control i-body (21H5) had no effectin the inhibition assay as expected.

Cell Viability

In a second experiment it was demonstrated that the i-bodies did notcause loss in viability of the cells used for HIV infection.

Method

For the HIV inhibition assay, NP2-CD4/CXCR4 cells (1×10⁴ in 100 μl) wereseeded in flat-bottom 96-well plates 24 h prior to addition of i-body(negative control i-body 21H5, and anti-CXCR4 i-bodies AM3-114, AM4-272,AM3-523, AM4-746 or AM4-1121). Media was then removed from the cells andreplaced with 100 μl of fresh media with five-fold dilutions of i-bodyfor 16 hr at 37° C. The concentration range for the CXCR4 i-bodies was25 μg/ml to 0.008 ug/ml. The concentration of PBS (5.8%, vol/vol) wasmaintained in the untreated wells. Following this, the media was removedand replaced with fresh media. The i-body concentrations were maintainedthroughout the subsequent culture period. NP2-CD4/CXCR4 cells wereincubated at 37° C. for a total of 72 h. The cell viability in each wellwas assessed using the CellTitre-Glo Luminescent Cell Viability Assay(Promega) according to the manufacturer's protocol. Luminescence wasmeasured using a FLUOStar microplate reader (BMG). To determine thepercentage cell viability in the presence of antibody, the amount ofluciferase in cells treated with the antibody was expressed as apercentage of that in untreated cells. The results are presented in FIG.21.

Inhibition of Virus Entry

All of the CXCR4 i-bodies appear to cause significant levels ofinhibition of two HIV-1 CXCR4-using envelope strains NL4.3 and1109-F-30. NL4.3 is a lab adapted Envelope whilst 1109-F-30 is a subtypeC clinical Envelope from a chronically infected individual. The i-bodiesdid not inhibit entry of an unrelated virus, VSVG, which is the Envelopefrom the Vesicular stomatitis virus which undergoes endocytosis afterbinding to an unrelated receptor, The results are presented in FIG. 22.

The negative control i-body, 21H5, had little effect on strain 1109-F-30but some invasion effect on strain NL4.3. By comparison, i-bodiesAM3-114, AM4-746 and AM4-1121 all inhibited both HIV strains very wellwith an IC₅₀ of around 80 nM. Furthermore, when i-bodies AM3-114 andAM4-746 were conjugated to PEG sized 30K (linear) and 2×20K (branched)the IC₅₀s remained consistently around 80 nM. Also consistent with theearlier experiment, AM4-272 was the least effective at blocking HIVinfection.

PEGylated i-bodies were assayed for their ability to block HIV infectioninto host cells. AM3-114 conjugated with 20K PEG, AM3-114 conjugatedwith 30K PEG and AM4-746 conjugated with 30K PEG were assayed for theability to block HIV invasion of three different virus strains. Thesewere compared with the non-PEGylated versions of the i-body. BothAM3-114 and AM4-746 were able to block HIV invasion in a similar fashionto the non-PEGylated versions, with only a slight reduction in thepotency of the PEGylated i-bodies compared to the non-PEgylated i-bodies(FIG. 23-1)

The PEGylated i-bodies and non-PEGylated ibodies are not able to blockHIV entry into host cells by a strain of HIV (YU-2) that relies on CCR5for entry (FIG. 23-2). This demonstrates that the anti-CXCR4 activity ofthe i-bodies are critical for blocking HIV entry.

Method

NP2-CD4/CXCR4 cells (1×10⁴ in 100 μl) were seeded in flat-bottom 96-wellplates 24 h prior to infection. The anti-CXCR4 antibodies wereresuspended in phosphate buffered saline (PBS). Prior to infection themedia was removed from cells and replaced with 100 μl of fresh mediawith five-fold dilutions of i-body (at a ×2 concentration) for 30 min at37° C. The concentration range for the CXCR4 antibodies was 25 μg/ml to0.008 ug/ml. The concentration of PBS (5.8%, vol/vol) was maintained inthe untreated wells. NP2-CD4/CXCR4 cells were infected with 200 TCID50of Env-pseudotyped luciferase reporter viruses in 100 μl for 12 h at 37°C. Following this, the inoculum was removed and replaced with freshmedia. The i-body concentrations were maintained throughout thesubsequent culture period. NP2-CD4/CXCR4 were incubated at 37° C. for atotal of 72 h. The level of HIV-1 entry was measured by luciferaseactivity in cell lysates (Promega) according to the manufacturersprotocol. Luminescence was measured using a FLUOStar microplate reader(BMG). Background activity was assessed by mock-infected cells and wassubtracted from all wells. To calculate the percentage of HIV-1 entry inthe presence of i-body, the amount of luciferase in cells treated withan i-body was expressed as a percentage of that in untreated cells.

Example 14—Lack of Stem Cell Mobilisation by i-Bodies

Plerixafor or AMD3100 is a small molecule bicyclam CXCR4 inhibitor,which has been approved for use in combination with G-CSF for HSCmobilisation. CXCR4 inhibitors of the prior art are known to cause stemcell mobilisation. As demonstrated in the experiments shown in thisExample, i-bodies of the present disclosure lack the ability to causemobilisation of stem cells.

14.1 Assessment of Specificity of CXCR4 Antibodies to VariousHaemopoietic Cells.

To confirm direct binding of CXCR4 antibodies (FLAG-tagged) to varioushaemopoietic cell populations, bone marrow cells harvested from C57/BL6mice were stained with a cocktail of five CXCR4 i-bodies (AM4-272,AM4-746, AM4-1121, AM3-114 or AM3-523) and then secondarily labelledwith a fluorescent anti-FLAG antibody. These cells were stained forlineage, progenitor and HSC markers and CXCR4 expression assessed onvarious haemopoietic cell populations. The results of this experimentvalidate CXCR4 i-body activity on primary mouse haemopoietic cells. Thesame experiment was performed on bone marrow cells harvested fromhumanised NSG mice to validate CXCR4 i-body activity on primary humanhaemopoietic cell populations (data not shown).

The i-bodies were all able to bind to bone marrow cells and human cordblood, which were CD34⁺ and CD38⁻.

14.2 Mobilisation of Mouse LSK and LSKSLAM Cells

To acquire evidence of haemopoietic stem cell mobilisation using CXCR4i-bodies, mice were injected with a CXCR4 i-body (AM4-272, AM4-746,AM4-1121, AM3-114 or AM3-523) by i.v. injection (5 mice/group). After 1and 3 hours, mice were euthanized and peripheral blood (PB) harvested.Spleens were harvested and weighed to assess for splenomegaly(enlargement of the spleen). PB was counted to assess white blood cellcontent as shown in FIG. 24A. Samples were lysed to remove red bloodcells and 4000 cells plated for LPP (low-proliferative potential) andCFU-HPP (colony forming unit-high proliferative potential) colonies(colony counting 7 days post-plating). The remaining cells were stainedwith an antibody cocktail to assess lineage-committed, stem andprogenitor cell content. Flow cytometric analysis was used to calculatenumbers of lineage-committed cells, haemopoietic stem and progenitorcells as well as enriched HSC per volume of PB. No mobilisation of whiteblood cells was detected with any of the i-bodies (AM4-272, AM4-746,AM4-1121, AM3-114 or AM3-523 FIG. 24A) compared to the positive controlAMD3100. Lack of mobilisation of murine Lin⁻, Sca-1⁺, c-Kit⁺ (LSK cells)is shown in FIG. 24B against a positive control AMD3100. No mobilisationof LSK cells was achieved by the i-bodies when compared to positivecontrol AMD3100.

FIG. 24C shows lack of mobilisation of Lin⁻, Sca-1⁺, c-Kit⁺, CD150⁺,CD48⁻, (CD34⁻) LSKSLAM cells by i-bodies. Again, no mobilisation wasobserved for all i-bodies.

14.3 Mobilisation of Human CD34+ Cells

To acquire evidence of mobilisation of human CD34⁺ stem and progenitorcells using CXCR4 i-bodies, the above mobilisation experiment wasconducted in humanized NODSIL2Rγ (NSG) mice. NSG mice are severelyimmunodeficient and lack mature T cells, B-cells and NK cells and haveseverely defective innate immunity, which allows engraftment of humancells without subsequent rejection. NSG mice were transplanted withfreshly sorted CD34⁺ cord blood cells and upon confirmation of positivehuman CD45/CD34 engraftment (˜4-5 weeks) were used as a mouse model forhuman stem cell mobilisation.

Humanised NSG mice were treated with 21H5 i-body, CXCR4 i-bodies(AM3-114 and AM3-523) and positive control AMD3100, which has previouslydemonstrated to give significant mobilisation of CD34⁺ cells in thismodel.

Mobilised peripheral blood was harvested and assessed for CD34⁺ (humanstem and progenitors).

Preliminary experiments with i-bodies AM3-114 and AM4-523 as shown inFIG. 25 demonstrate that these i-bodies do not mobilise stem cellscompared to the positive control AMD3100 in a humanised NODSIL2Rγ (NSG)mouse model. This finding is significant and represents a departure fromCXCR4 inhibitors of the prior art which are known to cause stem cellmobilisation.

14.4 Confirmation of Binding of i-Bodies to Stem Cells

To determine whether CXCR4 i-bodies bind HSC, in vitro binding analysisto human CD34⁺CD38⁻ cells was assessed. Umbilical cord blood (CB) andhuman bone marrow (BM) were collected as previously described (Nilsson SK et al, 2005 15; 106(4):1232-9; Grassinger, 2009 2; 114(1):49-59).Enriched human BM CD34⁺ cells and purified CB CD34+ cells were isolatedas previously described (Grassinger, 2009). Human CB and BM CD34+ cellsand huNSG BM were stained sequentially with CXCR4 i-bodies (10 μg/ml),anti-His-PE and an antibody cocktail containing CD34-FITC (BD Biociences#348053) and CD38-BV421 (BD Horizon #562444), washed with PBS (0.5% BSA)and analysed by flow cytometry on a Cytopeia Influx (BD) as previouslydescribed (Grassinger, 2009). For analysis of human and murine BM andPB, up to 5×10⁶ cells were analyzed at 10-20,000 cells/sec. Data wereanalyzed using FlowJo 10 software (FlowJo, LLC). For analysis of huNSGBM, huCD45-PECy7 (BD Biosciences #557748) and muCD45-BUV395 (BDBiosciences #564279) were also included in the antibody cocktail. HSCfrom human CB and BM were defined as CD34+CD38− and HSC from huNSG micewere defined as muCD45⁻huCD45⁺CD34⁺CD38⁻. CB and BM samples from 3individual donors and BM from 3 individual huNSG mice were assessed.

I-bodies AM3-114, AM4-272 and AM3-523 effectively bound human Cord BloodHSC in decreasing avidity (FIG. 26). AM3-114 also effectively bound tohuman Bone Marrow HSC and Bone Marrow harvested from humanizedNODSCIDIL2Rγ^(−/−) (huNSG) mice (FIG. 26).

Example 15—Prevention of Fibrosis by i-Bodies 15.1 Corneal Alkali BurnModel

Fibrosis induction (corneal neovascularisation (NV)) by the i-bodies canbe examined using the corneal alkali burn model as described in Cai X etal (2014) PLoS ONE 9(2):e88176. The method involves anesthetising rats(e.g. Sprague Dawley) with an intraperitoneal injection of 60 mg/kg ofNembutal and the topical administration of a drop of tetracaine. Acorneal alkali-wound is made by placing a 1.5 mm diameter circular pieceof filter paper, soaked in 1 N naOH, in contact with the central corneaon the right eye for 40 sec. Immediately after alkali exposure, theocular surface is rinsed with PBS for 60 sec. The rats are randomlydivided into 2 groups (n=15): Group 1 comprising rats subjected toalkali burn with normal saline treatment (10 μl, 4 times per day), andGroup 2 comprising rats subjected to alkali burn with TMP treatment (1.5mg/ml in a volume of 10 ml, 4 times per day). All eyes are then observedon day 28 using slit lamp microscopy for the evaluation of corneal NV.

15.2 Evaluation of NV in the Cornea

Corneal NV (NV) can be quantified as described in Zhang Z et al (2005)Invest Ophthalmol Vis Sci 46:4062-4071 doi:10.1167/iovs.04-1330.Briefly, an ophthalmologist blinded to the study conditions examines alleyes under a slit lamp microscope on days 1, 2, 5 and 8 after alkaliburn. The corneal image is divided into 4 quarters. The vessel length ofeach quarter (Li, i=1-4) is measured using a Vernier caliper. Thecorneal NV area (A) is calculated using the following equation: A==1−43.1416×{R2−(R−Li)2} (R is the radius of the rat cornea. R=3.5 mm, ascalculated from the measurement of 15 rat corneas).

15.3 Choroidal Neovascularisation

The laser induced choroidal neovascularisation (CNV) is a wellcharacterised and accepted model of choroidal neovascularisation(Fletcher E L et al. (2011) Prog Mol Biol Transl Sci 100:211-286). It isalso a rapid method for determining the efficacy of potential treatmentsthat target angiogenesis and fibrosis. Briefly, up to four laser spotsare applied to the posterior eye using a continuous wavephotocoagulation laser (532 nM diode). The laser energy is high enoughto create a break in Bruch's membrane. During the following 7-14 days,growth of blod vessels from the choroid into the retina occurs, and isquantified either immuocytochemically, or using fluorescein angiography.

Briefly, a total of twenty (20) Dark agouti rats or C57BL/6 mice housedin a Biomedical Animal Facility in a cyclic light environment (12 hourson, 12 hours off, at an in-cage luminance of <350 lux) for 10 days ormore before use are anaesthetised and treated with a 532 nm continuouswave thermal laser applied as 4 spots around the optic nerve.Immediately following laser treatment, animals are treated with thehighest dose of i-body (concentration at the retina being 20 mg/ml).

The structure of the retina of all rats is examined with a dedicatedrodent fundus camera/OCT (Micron III, Phoenix Insruments), and theintegrity of the vascular quantified using fluorescein angiography. Thesize (diameter and area) of all fluorescent lesions is then quantifiedto provide a measure of the extent of angiogenesis.

Following imaging, the animals are killed by anaesthetic overdose andthe posterior eye cups fixed in 4% paraformaldehyde for 30 mins. Retinalwholemounts are then processed for IB4 labelling to assess the extent ofthe growth of choroidal vessels into the subretinal space. The diameterand area of the lesion provides an assessment of the extent ofneovascularisation.

In addition, the level of scarring that develops as a consequence ofinvasion of choroidal blood vessels is quantified by immunolabelling forthe gliotic marker GFAP.

In addition retinal contraction, lesion size, alteration in microgliaand glial response and pro-fibrotic gene expression in the treatedretinas following laser treatment is also examined to evaluate fibrosis.

The anti-CXCR4 i-body AM3-114-6H (plus a control i-body) reducespathological angiogenesis or lesion characteristics in a mouse model ofchoroidal neovascularization. The levels of CXCR4 have been examined inthe eye following laser treatment (PCR fibrosis array; SABiosciences)and were shown to be dysregulated. The upregulation of CXCR4 in thissetting suggests that treatment with CXCR4 antagonist i-bodies couldhave a beneficial effect.

Mice were treated as below:

-   -   Group 1 (n=10): laser both eyes-vehicle in one eye; i-body in        the other    -   Group 2 (n=10): Laser one eye (no i-body); other eye unlasered.        The i-body drug was injected intravitreally in 1 μl volume at a        concentration up to 20 mg/ml.

Data of the effects of the i-bodies on the retinal contraction, lesionsize and gene expression in the treated retinas following lasertreatment was obtained. There was a dramatic contraction of the retinafollowing laser treatment compared with unlasered regions in the sameeye. Treatment with both AM3-114 and AM4-272 resulted in significantreduction in the contraction of the lasered regions. One confoundingfactor was that the vehicle controls also seem to have a verysignificant reduction in the ratio of contraction. Since the vehicleconsists of only a single injection of TBS it is unlikely that thiswould have such an effect. The more likely explanation is that i-bodyhas actually escaped from the treated eye and entered the circulationperhaps blocking inflammatory cells from infiltrating the vehicletreated eye. There was also a reduction of the lesion size uponadministration of the i-body AM3-114.

The expression of genes associated with angiogenesis and fibrosis wasexamined. Total RNA was isolated from the retina and RPE/choroidalsamples using commercial spin columns (RNeasy, Qiagen, Valencia Calif.).A PCR gene array was used to assess the expression of 84 genes involvedangiogenesis or fibrosis (Qiagen). Briefly, total RNA samples fromuntreated, laser treated eyes and untreated fellow eyes (n=9 each group,each 25 ng) were pooled within their respective treatment groups (3independent experiments containing 3 pooled samples), reversedtranscribed (RT2 first strand, Qiagen) and then underwentpre-amplification of the cDNA target templates (RT2 pre-AMP, Qiagen).Samples were added to a commercial mastermix (RT2 SYBR green mastermix,Qiagen) and amplified for 40 cycles (ABI 7900HT, Life Technologies,Grand Island N.Y.). Three independent arrays were performed for eachtreatment group. The data were analysed using delata delta Ct (ΔΔCt),expressed as fold change and regulation assessed using an unpairedt-test. This gene expression data from both AM3-114 and AM4-272 treatedeyes which indicates that there is extensive down regulation of profibrotic genes such as Col1A2, TGF-b1, connective tissue growth factor(CTGF) and Tissue inhibitor of metalloproteinase (TIMP3), Thrombospondin2 (Thbs2), serine peptidase inhibitor (SerpinH1), Integrin β8 subunit(ITGB8), Lysyl oxidase (LOX), Eotaxin (CCL11), β3 integrin (ITGB3),serine-threonine protein kinase (Akt1), SMAD family member 6 (SMAD6),Platelet-Derived Growth Factor Alpha Polypeptide (PDFGA), TransformingGrowth Factor, Beta Receptor II (Tgfbr2), Bone Morphogenetic Protein 7(Bmp7), (FIG. 27).

Example 16—Binding of i-Bodies to Fibrocytes

Circulating bone-derived mesenchymal cells that have the potential todevelop into fibrocytes and can play a critical role in the pathogenesisof fibrosis (Strieter R M, Keeley E C, Burdick M D and Mehrad B. TheRole of Circulating Mesenchymal Progenitor Cells, Fibrocytes, inPromoting Pulmonary Fibrosis. Trans Am Clin Climatol Assoc 2009; 120;49-59) and that cells expressing CD45 and CXCR4 are circulatingfibrocytes that can migrate in response to SDF-1 and traffic to thelungs in a murine model of bleomycin-induced pulmonary fibrosis(Phillips R J, Burdick M D, Hong K, Lutz M A, Murray L A et al.Circulating fibrocytes traffic to the lungs in response to CXCL12 andmediate fibrosis. J Clin Invest (2004) 114: 438-44).

Double labeling of i-body (AM3-114) and CD-45 was performed as follows.I-body AM3-114 was incubated with isolated human PBMCs at roomtemperature for 4 hours. PBMCs were smeared on a microscope slide andfixed with acetone at 4° C. for 10 minutes. Following three timeswashing and rehydration with PBS the slides were incubated with mouseantiFLAG 1:100 dilution over night at 4° C. After washing the slideswere incubated with Goat anti-mouse Alex Fluor 568 (to detect i-body bybinding anti FLAG) at room temperature for 1 hour. The slides were thenwashed and incubated with Mouse anti-CD-45 FITC labeled antibody overnight at 4° C. After further washing the slides were and mounted withProLong Gold antifade mountant containing DAPI. Images were captured byusing Nikon A1 confocal microscope.

Human fibrocytes were identified by staining with an antibody to CD45.Binding of i-body AM3-114 was identified by an anti-FLAG antibody to theC-terminal tag. DAPI was used to stain the nucleus of the cells. Theresults are presented in FIG. 28. The results show that i-body AM3-114was capable of binding to human fibrocytes.

Example 17—In Vivo Murine Air-Pouch Model

The ability of i-bodies to block inflammation was evaluated in an invivo murine air pouch model. The subcutaneous (s.c.) air pouch is an invivo model used to study acute and chronic inflammation (Durate et al,Models of Inflammation: Carrageenan Air Pouch, Current Protocols inPharmacology 5.6.1-5.6.8, March 2012). Injection of irritants into anair pouch in rats or mice induces an inflammatory response that can bequantified by the volume of exudate produced, the infiltration of cells,and the release of inflammatory mediators. An air pouch, is generated byinjection of sterile air under the skin of the back of the mouse. Themouse is pretreated with either the anti-inflammatory compound or testarticle (i-bodies or AMD3100), and secondarily treated with SDF-1, theinducer of inflammation. Air pouch lavage fluid is then analyzed forcell trafficking and cytokine release.

The air pouch assay was performed on 7-week-old BALB/c mice. On days 1and 3, 0.2 ml/g initial body weight (IBW) of sterile air was injectedunder the back skin to create the pouch. On day 6, mice were divided ingroups and received an intraperitoneal injection of 0.5 ml of PBScontaining or not containing the i-body (AM3-114, AM4-272, AM3-523,AM4-746 or AM4-1121) or AMD3100 (10 mg/kg). Thirty minutes later, SDF-1(6 μg) was injected into the pouch. Four hours later, the mice werekilled in a CO₂ chamber and the air pouch was washed. Cells werecollected, counted, and characterized by flow cytometry.

Total cells in the air pouch demonstrate that the test articles inhibitthe migration of cells into the airpouch/site of inflammation. Thei-bodies AM3-114, AM4-272, AM3-523, AM4-746 and AM4-1121 inhibited cellmigration to the airpouch (similar to AMD3100) however the negativecontrol i-body (21H5) did not inhibit cell migration. I-bodies injectedinto the mouse without the inflammatory stimulant had no effect onmigration of cells to the air pouch (FIG. 29).

Example 18—Prevention of Idiopathic Pulmonary Fibrosis (IPF) in aBleomycin Mouse Model

The ability of the CXCR4 binding molecules (i-bodies) to inhibitpulmonary fibrosis was examined in a mouse model of disease. Bleomycin,an antibiotic and anti-tumour agent, is widely used in experimentalmodels of human disease resembling IPF. Bleomycin is able to cause celldamage independent from its effect on DNA by inducing lipidperoxidation. The precise nature of the interaction between bleomycinand the lung that leads to collagen deposition is uncertain. However,over-activation of cytokines and growth factors such as IL-1, IL-6,TNF-alpha, PDGF and TGF-beta has been consistently implicated in thedisease progression. Recent evidence suggests that antagonising CXCR4 iseffective in preventing the pulmonary fibrosis in the bleomycin mousemodel.

The mouse IPF model is a validated model of inflammation and fibrosis,with initial (within 48 hours) lung injury characterised histologically,by perivascular oedema, capillary congestion and alveolar wallthickening associated with intra-alveolar haemorrhage and inflammatorycell infiltrate in the alveolar walls as well as in the spaces. Focalperibronchial and subpleural collagen deposition usually follows withina week after bleomycin administration in this model.

The optimal dose of Bleomycin is 2 U/mouse and the optimal time forassessing fibrocyte recruitment was confirmed at day 4. At days 4bronchoalvelolar lavage (BAL) fluids were collected for analysis ofSDF-1 concentration. One half of the lung tissue was used to make singlecell suspensions of the lung and the cells used for flow cytometry andassayed for CD45+, CXCR4+ and Collagenl+(fibrocytes). The other half ofthe lung tissue was Sircol stained for the presence of collagen 1 andRNA will be tested for Col-1, Col-3 and SDF-1.

Using 2 U Bleomycin/mouse (10 per group) mice were dosed with i-bodies,negative control i-body 21H5 at 30 mg/kg and anti-CXCR4 i-bodies,AM3-114, AM4-272, AM3-523 at 1, 10 and 30 mg/kg. SDF-1, fibrocytes andcollagen deposition were monitored at Day 4. Groups were dosed with thei-body just prior to administration with Bleomycin. One half of the lungtissue was minced and washed in PBS and used to make single cellsuspensions of the lung with Collagenase A and dispase treatment. Thecells were then used for flow cytometry and assayed for CD45+, CXCR4+and Collagenl+ fibrocytes.

Administration of i-body AM3-114 at 30 mg/kg was able to dramaticallyattenuate the recruitment of fibrocytes into the lungs of mice withBleomycin induced fibrosis. It was also evident that i-bodies AM4-272and AM3-523 were able to significantly attenuate the recruitment offibrocytes into the lungs of these mice. I-bodies AM4-272 and AM3-523were able to block recruitment of fibrocytes even at 1 mg/Kg. Asexpected, AMD3100 and Perfenidone were also able to block recruitment offibrocytes. Neither the vehicle alone nor the negative control i-bodyaffected recruitment of fibrocytes into the lungs of mice with Bleomycininduced fibrosis (FIG. 30).

The lung tissue was examined using the Sircol staining assay (BiocolourLtd., Carrickfergus, Northern Ireland) according to the manufacturer'sprotocol, to determine the presence of the extracellular matrix proteincollagen. i-body AM3-114 at 30 mg/kg, i-body AM4-272 at 10 mg/kg andi-body AM-3523 at 30 mg/kg all reduced the collagen content of the lungas compared to the vehicle alone or the negative control i-body (21H5).A reduction in collagen was also seen for AMD3100 and Pirfenidone.

A Bleomycin pulmonary fibrosis experiment in mice was performed over 21days to assess the effect of PEGylated i-body. Administration ofPEGylated i-body AM4-272 at 10 mg/Kg was able to attenuate therecruitment of fibrocytes into the lungs of mice with Bleomycin inducedfibrosis at day 7. AM4-272-PEG decreased fibrocytes at day 7 to aboutthe same extent as AMD3100 and Pirfenidone.

Subsequently the remaining lung tissue was used to analyse the RNA fromeach sample for CXCL12, Col1a1 and Col3a1 gene expression as perPhillips et al (2004) J Clin Invest 114, 438.

Example 19 Epitope Mapping

Shotgun mutagenesis (Integral Molecular) was used to evaluate anti-CXCR4i-bodies AM3-114, AM4-272 and AM3-523 binding to wild-type and mutatedhuman CXCR4. The i-bodies were tested against HEK-293 T cells expressingCXCR4. Optimal screening conditions were determined for theimmunodetection and epitope mapping of i-bodies AM3-114 (1 μg/ml),AM4-272 (2 μg/ml) and AM3-523 (1 μg/ml) which gave a highsignal-to-background value. The mean i-body reactivities (and ranges)are shown in Table 13 for all critical residues identified in thescreen. Control antibodies were anti-flag and 12G5 which arecommercially available.

Critical residues of the CXCR4 protein for i-body binding (grey) wereidentified as those that were negative for i-body binding (<30% WT forAM3-114 and AM4-272; <15% for AM3-523) but positive for the anti-FlagmAb (>70% WT), and also positive for an additional control mAb 12G5(>50% WT).

All three i-bodies had residue D262 in common which AMD3100 also binds(Haste et al., (2001) Molecular Pharmacology 60:164-173). All criticalamino acids identified by the epitope mapping are conserved betweenhuman and mouse CXCR4 except for F189. No binding agents have beenpreviously identified that bind to residues E32 or L266 of CXCR4.

An additional set of residues also had an effect on the binding of somei-bodies they are; C28, V112, D193, P191, E268 and E288

Example 20—i-Body Binding to CXCR4 in Human Patient Tissues withIdiopathic Pulmonary Fibrosis (IPF)

To further confirm the expression of CXCR4 in normal and IPF lungs,negative control i-body 21H5, CXCR4-specific iBodies (AM3-114, AM4-272and AM3-523) were utilized in Immunohistochemical (IHC) analysis (datanot shown). Few CXCR4 expressing cells were detected in normal andslow-IPF lung biopsies. CXCR4 expressing cells were readily detected inrapid-IPF lung biopsies. Finally, CXCR4 was detected with the i-bodiesin interstitial cells present in fibrotic regions of rapid-IPF lungbiopsies. The i-bodies of the present disclosure were able to bind tothe fibroblasts from IPF patient lung biopsies (both rapid and slowproressors) but did not bind to lung biopsies from normal lung tissue.

Example 21—Reduction of Human Lung Fibroblast Invasion from IdiopathicPulmonary Patient Tissue

Several reports have shown evidence for a role of CXCL12 and CXCR4 inlung invasion (Li et al Cancer Lett 2012 322; 169-176 & Krook et al MolCancer Res 2014 12; 953-964). Lovgren, A et al have shown thatβ-arrestin plays an important role in lung fibroblast invasion (Lovgrenet al Sci Transl Med 2011 3; 74ra23). Further, several reports haveshown that CXCR4 delivers CXCL12 to CXCR7, leading to the activation ofthe β-arrestin pathway, suggesting that CXCR4 may promote invasion oflung fibroblasts (Coggins et al. 2014 PLoS One 9, e98328, Decaillot etal. J Biol Chem 2011 286; 32188 32197, & Rajagopal et al PNAS 2010 107;628-632).

To determine the role of CXCR4 and CXCL12 in fibroblast invasion, normaland IPF lung fibroblasts were utilized in a wound healing invasionassay. ImageLock 96 well plates (Essen Bioscience) were coated with 50μg/ml of Basement membrane extract (BME; Trevigen) for one hour at roomtemperature. Normal, and fibroblasts generated from lung biopsies ofidiopathic pulmonary fibrosis (IPF) patients showing slow progression orrapid progression of the disease were plated (36,000 cells per well) onthe BME-coated plates and incubated overnight. The following day, cellswere scratched using a Woundmaker™ (Essen Bioscience), washed with DPBStreated with negative control i-body 21 h5, CXCR4-specific iBodies(AM3-114, AM4-272; 130 μg/ml) or AMD3100 (12 μM) in a 2 mg/ml BMEsolution. The BME was allowed to polymerize by incubating the plate at37° C. for 15 minutes. The plates were then inserted into an IncuCyteZoom imaging system and images were acquired every 2 hours forapproximately 50 hours. Invasion was quantified using IncuCyte software(Essen Bioscience).

BIBF-1120, a multiple receptor tyrosine kinase inhibitor currentlyapproved for the treatment of IPF, effectively inhibited both normal andIPF fibroblast motility. CXCR4 specific iBodies AM3-114-6H andAM4-272-6H inhibited invasion in slow-IPF and two out three rapid-IPFbut not normal lung fibroblasts (FIGS. 31-1 to 31-3 shows representativeexamples of fibroblasts form normal, slow and fast IPF patients).

Example 22—i-Bodies Exhibit Anti-Fibrotic Properties In Vitro

To determine potential roles for CXCR4 in lung fibroblast activation andextracellular matrix generation fibroblasts were treated with CXCR4specific i-bodies (AM3-114-6H, AM4-272-6H, AM3-523-6H), negativecontrol-iBody (21H5) or AMD3100 for 48 hours after which RNA wasextracted and qPCR analysis was performed for ACTA2, COL1A1, COL3A1 andFN1 transcripts. The qPCR method was as follows: Fibroblasts were platedon 50 μg/ml of BME and treated with 130 μg/ml of iBodies or 12 μM ofAMD3100. After 48 hours, RNA was extracted using Trizol reagent andreverse transcribed into cDNA using superscript II reverse transcriptase(Life technology) as previously described (Trujillo et al Sci Transl Med2010 2; 57ra82). Complementary DNA (cDNA) was subsequently loaded into aTaqman plate and gene expression analysis were performed usingpredesigned primers for COL1A1, COL3A1, FN1, and αSMA. All Taqmananalysis was performed using an Applied Bio system's Viia 7 instrument(Life technology). The results were then exported, normalized to 18s RNAexpression and fold change analysis were calculated using Data Assistsoftware (Life technologies). CXCR4 specific AM3-114-6H markedly reducedpro-fibrotic gene transcript expression of ACTA2, COL1A1, COL3A1 and FN1in Slow-IPF but not normal lung fibroblasts (FIG. 32).

In order to examine whether the i-bodies could modulate soluble collagenin IPF lung fibroblasts an ELISA was used. Collagen 1 was detected usinga direct ELISA. Briefly, purified collagen 1 protein and conditionedsupernatants were coated on maxi-sorb ELISA plates overnight at 4° C.The next morning, plates were washed, blocked with 1% BSA for one hourand then incubated with a biotinylated anti-Collagen 1 antibody (Abcam)for 2 hours on a rotating shaker at room temperature. Plates were thenwashed and HRP-conjugated strepdavidin was added to the wells for 20minutes. After 20 minutes, the plates were washed and developed with TMBsubstrate for 20 minutes after which a stop solution was added and theabsorbance was acquired at 450 nm using a Synergy H1 microplate reader(Biotek).

The CXCR4 specific iBody, AM4-272-6H, markedly reduced soluble collagenprotein in conditioned supernatants of fibroblast 48 hours posttreatment with the iBody.

Example 23—i-Bodies Modulate Various Signalling Partners

Various reports indicate that CXCR4 signals in conjunction with otherchemokine receptors, including CCR2. To determine whether CXCR4 specificiBodies may modulate potential CXCR4 signaling partners, conditionedsupernatants were collected from normal, slow- and rapid-IPF lungfibroblast culture 48 hours post iBody (AM3-114-6H or AM4-272-6H),AMD3100 or BIBF-1120 treatment and CCL2, CCL5 and CXCL12 were detectedin fibroblast-conditioned supernatants using commercial ELISA kits asrecommended by the manufacturer (R&D Systems). The CXCR4 targetingiBodies, AM3-114-6H and AM4-272-6H, AMD3100 and BIBF-1120 markedlyincreased CCL2 protein in IPF but not normal fibroblast conditionedsupernatants, which was evident in rapid-IPF lung fibroblast conditionedsupernatants. The CXCR4 targeting iBody, AM4-272-6H, increased CCL5levels in some IPF lung fibroblasts; however, this effect was notconsistent and was observed in one slow-IPF lung fibroblast line treatedwith the control iBody, 21H5-6H.

Example 24—i-Bodies Block Platelet Aggregation

Experiments were carried out to examine whether the i-bodies could blockplatelet aggregation induced by SDF-1α. Human platelet rich plasmasuspensions were pre-incubated with the i-bodies AM3-114, AM3-523,AM4-746 or AM4-1121 (or 12G5 positive control anti-CXCR4 Mab) at 10 or20ug/mL for 10 min, followed by stimulation with 100 nM SDF-1 alpha. Inthe presence of negative control i-body 21H5 (or the isotype control for12G5: mouse IgG2a). SDF-1 induced a robust and reproducible aggregation(the descending black curves, which indicate an increase in lighttransmission), which matches with what has been previously published.All the i-bodies as well as 12G5 had an inhibitory effect with AM3-114and AM4-1121 being the most efficient (FIG. 33). These i-bodies showed astrong and sustained blocking of aggregation. AM3-523 and AM4-746blocked aggregation to the same extent as the MAb12G5, and AM4-272blocked aggregation only weakly. Neither the negative control i-body northe control MAb had any effect on platelet aggregation.

Example 25—Anti CXCR4 i-Body is Active in a Mouse Model of MultipleScelerosis (Experimental Autoimmune Encephalomyelitis)

Holman et al (Biochimica et Biophysica Acta 2011) There have been a somepublications suggesting demosntrated that CXCL12 is responsible forrecruiting CXCR4 positive cells across the blood brain barrier aroundthe day 8-12 time points in Experimental autoimmune encephalomyelitis(EAE), mouse model of multiple sclerosis. In addition recent studiesdemonstrated that CXCR4 antagonists showed efficacy in EAE (Hanes et alJBC Vol 290(37):22385-22397 (2015), Kohler et al Brain Pathology 2008,18; 504-516). The inventors induced EAE in a small number of animals(n=3 per group) by injection of myelin oligodendrocyte protein (MOG) atday 0 and treated them with i-body AM4-272 intravenously at 4 mg/Kgbetween day 7-10 (one injection/day for 4 days). This is the time thathas been reported to be critical for infiltration of inflammatory cellsacross the blood brain barrier. It was noted that of the three miceinjected with the AM4-272 i-body, one progressed to the disease whereasthe other 2 were almost disease free. The bodyweights of the animalstreated with i-body at day 15 is significantly different from diseaseanimals or those injected with negative control i-body 21H5. Inaddition, the clinical scores were dramatically improved by injectionwith i-body as compared to disease animals or those injected withcontrol i-body at both day 14 and day 15 (FIG. 34). These data suggestthat the i-bodies of the current invention can bind to CXCR4 on theinflammatory cells and inhibit their migration form the peripheral bloodsystem into the brain. It appears that blocking this migration canalleviate the symptoms of EAE.

Immunohistochemistry of the brains of the experimental mice wasperformed. A large amount of inflammatory cell staining was seen in thewhite matter of the brains of diseased animals (MOG only) and in thesymptomatic mouse given the AM4-272 i-body. Whereas there was verylittle inflammatory T-cell staining in the vehicle control or in theasymptomatic mice given AM4-272 i-body.

Initial Hematoxylin and eosin staining has been carried out on the braintissue of EAE mice with and without i-body (AM4-272) treatment tohighlight T-cell infiltration into the white matter. Dramatic T-cellinfiltration was observed in the MOG mice treated with the controli-body 21H5 but not in the mice treated with the AM4-272 i-body.

1-41. (canceled)
 42. A polypeptide which binds to human CXCR4,comprising a scaffold region and complementarity determining regions(CDR1 and CDR3) contained therein, the scaffold region comprising asequence which has at least 75% identity to the scaffold region definedby amino acids 1 to 26, 33 to 79 and 88 to 97 of SEQ ID NO:1; andwherein the CDR1 and CDR3 region defined by amino acids 27 to 32 and80-87 respectively of SEQ ID NO:1 are modified by amino acid addition orsubstitution therein; and wherein the CDR3 region comprises or consistsof a sequence having at least 70% identity to SEQ ID NO: 13, SEQ ID NO:16, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQ ID NO: 28, or SEQID NO:
 31. 43. The polypeptide according to claim 42, wherein thescaffold region comprises between 1 and 5 amino acid additions orsubstitutions within the sequence set forth in SEQ ID NO:2 or comprisesthe sequence set forth in SEQ ID NO:2.
 44. The polypeptide according toclaim 43, wherein the amino acid designated by A′ at position 23 of SEQID NO:2 is the amino acid residue glutamine (Q) or lysine (K); and theamino acid designated by B′ at position 24 of SEQ ID NO:2 is the aminoacid residue valine (V) or alanine (A).
 45. The polypeptide according toclaim 42, which is an antagonist of human CXCR4.
 46. The polypeptideaccording to claim 42, wherein: the CDR3 region comprises or consists ofa sequence having at least one, two, three, four or five amino acidsubstitutions within a sequence selected from SEQ ID NO:13, SEQ ID NO:16, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 25, SEQ ID NO: 28, or SEQID NO: 31; or (ii) the CDR1 region comprises or consists of a sequencehaving at least 50% identity to SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO:18, SEQ ID NO: 21, SEQ ID NO: 24, SEQ ID NO: 27, or SEQ ID NO:30; or(iii) the CDR1 region comprises or consists of a sequence having atleast one, two, three, four or five amino acid substitutions within SEQID NO:12, SEQ ID NO: 15, SEQ ID NO: 18, SEQ ID NO: 21, SEQ ID NO: 24,SEQ ID NO: 27, or SEQ ID NO:30.
 47. The polypeptide according to claim42, wherein the polypeptide comprises: (i) a CDR1 region sequence havingat least 50% identity to SEQ ID NO: 12 and a CDR3 region sequence havingat least 70% identity to SEQ ID NO: 13; (ii) a CDR1 region sequencehaving at least 50% identity to SEQ ID NO: 15 and a CDR3 region sequencehaving at least 70% identity to SEQ ID NO: 16; (iii) a CDR1 regionsequence having at least 50% identity to SEQ ID NO: 18 and a CDR3 regionsequence having at least 70% identity to SEQ ID NO: 19; (iv) a CDR1region sequence having at least 50% identity to SEQ ID NO: 21 and a CDR3region sequence having at least 70% identity to SEQ ID NO: 22; (v) aCDR1 region sequence having at least 50% identity to SEQ ID NO: 24 and aCDR3 region sequence having at least 70% identity to SEQ ID NO: 25; (vi)a CDR1 region sequence having at least 50% identity to SEQ ID NO: 27 anda CDR3 region sequence having at least 70% identity to SEQ ID NO: 28; or(vii) a CDR1 region sequence having at least 50% identity to SEQ ID NO:30 and a CDR3 region sequence having at least 70% identity to SEQ ID NO:31.
 48. The polypeptide according to claim 42, wherein the polypeptidecomprises: (i) a sequence that has at least 80% identity to SEQ ID NO:11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ IDNO: 26, or SEQ ID NO: 29; or (ii) the sequence set forth in any one ofSEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO:23, SEQ ID NO: 26, or SEQ ID NO: 29; or (iii) one, two, three, four,five, six, seven, eight, nine or ten substitutions within the sequenceselected from the group consisting of SEQ ID NO: 11, SEQ ID NO: 14, SEQID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29,SEQ ID NO:40, SEQ ID NO:44, SEQ ID NO:48, SEQ ID NO:52, SEQ ID NO:56,SEQ ID NO:60, SEQ ID NO:64, SEQ ID NO:68, SEQ ID NO:72, or SEQ ID NO:76.
 49. A polypeptide which binds to human CXCR4, comprising a scaffoldregion and complementarity determining regions (CDR1 and CDR3) containedtherein, the scaffold region comprising a sequence which has at least75% identity to the scaffold region defined by amino acids 1 to 26, 33to 79 and 88 to 97 of SEQ ID NO:1; and wherein the CDR1 region comprisesa sequence represented by the formula SX₁SX₂X₃R wherein X₁ is G, K, L orY; X₂ is D, H, G or N; and X₃ is I, V, M, F, Q or Y; or a conservativeamino acid substitution thereof and/or wherein the CDR3 region comprisesa sequence represented by the formula Y′₁RY′₂GY′₃YRHRY′₄LY′₅LG whereinY′₁ is Y or W; Y′₂ is T, V or I; Y′₃ is G or A; Y′₄ is A Or Y; and Y′₅is V, R or K; or a conservative amino acid substitution thereof.
 50. Thepolypeptide according to claim 49, wherein the CDR1 region comprises orconsists of the sequence set forth in any one of SEQ ID NO: 41, SEQ IDNO: 45, SEQ ID NO: 49, SEQ ID NO: 53, SEQ ID NO:57, SEQ ID NO:61, SEQ IDNO:65, SEQ ID NO:69, SEQ ID NO: 73, or SEQ ID NO:77; and/or wherein theCDR3 region comprises or consists of the sequence set forth in any oneof SEQ ID NO: 42, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 54, SEQ IDNO: 58, SEQ ID NO:62, SEQ ID NO:66, SEQ ID NO:70, SEQ ID NO: 74, or SEQID NO:78.
 51. The polypeptide according to claim 49 or 50: (i)comprising a sequence at least 75% identical to the sequence selectedfrom the group consisting of SEQ ID NO: 40, SEQ ID NO: 44, SEQ ID NO:48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQ ID NO: 64, SEQ IDNO: 68, SEQ ID NO: 72 or SEQ ID NO: 76; or (ii) comprising or consistingof the sequence set forth in any one of SEQ ID NO: 40, SEQ ID NO: 44,SEQ ID NO: 48, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 60, SEQ ID NO:64, SEQ ID NO: 68, SEQ ID NO: 72 or SEQ ID NO:
 76. 52. The polypeptideaccording to claim 42 which binds to one or more residues of CXCR4selected from the group consisting of C28, E32, V112, Y184, F189, P191,D193, W195, D262, L266, E268 and E288 of human CXCR4 (SEQ ID NO:105).53. An expression construct comprising the nucleic acid moleculeencoding the polypeptide according to claim
 42. 54. A conjugatecomprising a polypeptide according to claim 42 and an agent selectedfrom a therapeutic agent, a toxin, a detectable label or an agent whichextends the half-life of the polypeptide.
 55. A pharmaceuticalcomposition comprising the polypeptide according to claim 42 or theconjugate of claim 54 and an acceptable carrier.
 56. A polypeptideaccording to claim 42, or the conjugate of claim 54, for use in thetreatment or prevention of a CXCR4-related disease or disorder.
 57. Amethod of preventing or treating a CXCR4-related disease or disorder ora disease or disorder associated with CXCR4 signalling or a pathway ormechanism in which CXCR4 is involved, comprising administering to asubject in need thereof a polypeptide according to claim 42 or theconjugate of claim 54 or the pharmaceutical composition of claim
 55. 58.A method for localizing and/or detecting and/or diagnosing and/orprognosing a CXCR4-related disease or disorder, the method comprisingdetecting in vivo the polypeptide according to claim 42 bound to CXCR4,if present, wherein the polypeptide is conjugated to a detectable tag.